Geotripper

Photo by Mrs. Geotripper

In math, getting from Point A to Point B is hardly a problem. It's a straight line most of the time, or an arc, determined by some kind of equation. Getting from point A to point B can be a problem in a city, since buildings are often in the way, yet a good map or a vocal GPS unit gives you plenty of routes and choices to avoid traffic and delays.

Out in America's Never Never, the vast desert encompassing the Colorado Plateau and Basin and Range provinces, getting from Point A to Point B becomes a true challenge. Mountains may block the route, as the Forty-Niners found during the California Gold Rush (and earlier settlers like my ancestors, the Donners). There might be flat, open ground between one point and the other, but there might be no water. In a pre-automobile era, that was a serious problem. But out of all these examples the Colorado Plateau has one really impressive barrier: the Colorado River.

Photo by Mrs. Geotripper

What's the problem? It's a fair sized river as such things go, the biggest of the American Southwest, but it is hardly a trickle compared to many rivers back east and in the Pacific Northwest. Those rivers were barriers to travel, but numerous ferries and bridges soon solved access problems a long time ago (and numerous boats used the rivers themselves as a highway). The Colorado, though, is a geologically young river. It is rapidly cutting downward through the sedimentary and metamorphic rocks of the recently uplifted continental crust, and the consequence of this is an unnavigable rapid-filled river ensconced in a deep vertical gorge along its entire pathway through the plateau country. Until the Navajo Bridge (above, left) was constructed in 1928 the only place to cross the river between Moab, Utah and Needles, CA, a river distance of 600 miles, was at Lee's Ferry, about five miles upstream of Navajo Bridge (the completion of which put Lee's Ferry out of business). The ferry was the only spot on the river whose approach was not overly complicated by vertical cliffs.

There are more bridges today, but there is still a 300-plus mile stretch between Navajo Bridge and Lake Mead at Hoover Dam where there are no crossings (except the footbridge in Grand Canyon near Phantom Ranch). Travel through the Colorado Plateau country is still complicated by this fact (and frankly, it should remain so).

The paved highways give us a somewhat false sense of easy access, as they must also surmount or circumvent barriers in the landscape formed by river canyons and vertical cliffs. As long as there is gas in the tank, a working air conditioner, and properly tuned engine, we give little thought to how tenuous our control is over our localized environment. A flat tire on a deserted road on a blazing hot day can be life-threatening. And small geological events can have far-ranging consequences.

The original plan for our trip (conceived a year earlier) was to leave the North Rim of Grand Canyon and scoot down the slopes of the East Kaibab Monocline into the Navajo Section of the plateau country. We would cross the Colorado River at Navajo Bridge, turn at Bitter Water onto Highway 89 to Page, Arizona, where we would have a slow-paced tour of Horseshoe Bend, Glen Canyon Dam, and the incredible Antelope Canyon. From there it would be a fairly quick drive to Navajo National Monument, where we would be camping for the night. It was meant to be the most leisurely day of the trip.

Oh well....

The picture above gives a hint about how geology made our day a constant exhausting race against time. The Vermilion Cliffs are a prominent part of the Grand Staircase, revealing early Mesozoic formations, including the Chinle, Wingate and Kayenta. The Chinle, at the base, is composed of easily eroded shale and siltstone, and is subject to slope failure. In the picture above, looking across House Rock Valley, the lower slopes look tilted because they are part of a huge rotational slide.

If you take a big group through this region, you will need to make the camping reservations five or six months in advance, and even at that I nearly missed getting reservations for Arches National Park and the North Rim of Grand Canyon. As such, once the schedule has been established, it can't be easily changed.

But geology can change. Highway 89 from Bitter Water to Page starts out in spectacular fashion, climbing a slope of Chinle to a big cut through the Echo Cliffs, composed of the Wingate, Kayenta and Navajo formations. The view from the upper highway is a stunning panorama of Marble Canyon, the Vermilion Cliffs, and the East Kaibab Monocline that forms the margin of the Kaibab Plateau and Grand Canyon.

Photo by Mrs. Geotripper

The problem for the road engineers was getting across the Chinle slopes. The Chinle doesn't like highways on the flatlands (swelling and settling of the clays turns the best planned highways into roller-coasters), but it especially doesn't like roads on slopes.

Ultimately they chose to put the road across an ancient landslide not unlike the one in the Vermilion Cliffs above. It is especially visible in Google earth images, where a white outcrop of Navajo Sandstone can be seen well out of place next to the highway (below).

Source: GoogleEarth

In February, a portion of the old slide gave way, destroying a significant stretch of the highway. This wasn't the kind of slide that could be fixed easily, and the road will be out of service for a long time. The Echo Cliffs constitute a significant barrier to east-west travel, and between Bitter Water and Tuba City, only one dirt road crosses it. The state is in the process of paving the track, but it was nowhere near done when we passed through.

Source: Lee Allison, at http://arizonageology.blogspot.com/2013/03/adot-estimates-35-million-to-repair.html

If we were going to see the Navajo Bridge and the Colorado River, we would need to make a 140 mile detour to get to Page and our other objectives. And then backtrack around 70 miles.We barely made it to our tour appointment at Antelope Canyon at 3 PM. We got to see Horseshoe Bend, but the visit to Glen Canyon was cut very very short, and we didn't reach camp until well after dark.

Source: Arizona Department of Transportation

It was a long day...but spectacular, just the same. More later!

For more information about progress with Highway 89, check out http://www.azdot.gov/us89/

The Navajo flute player at work

The geology of Antelope Canyon is simple. Water (lots of it in a short time) and rock (specifically, the easily eroded but cliff-forming Navajo Sandstone). That's all it takes. There are other ingredients that make Antelope Canyon a memorable awe-inspiring experience: Sunlight and shadow for instance. The rock seems to glow with an internal golden light.

In the last post, I described the lengths we went to in order to arrive in Page, Arizona in time for our tour. These pictures should make clear why we tried so hard to add Antelope Canyon to our itinerary through America's Never Never, despite 140 mile detours. It is an extraordinary example of a sandstone slot canyon.

One thing that must be considered when visiting Antelope Canyon is whether you will visit the Upper Canyon or the Lower Canyon. The entrance fees are essentially the same, and you must be accompanied by a guide in each one.

The upper canyon is the most popular, probably for two reasons: it is a level walk on sand, and at the right time of day narrow beams of sunlight pierce the darkness of the canyon, which in places almost requires a flashlight (the entrance fee almost doubles for tours during those hours). It also requires being shuttled up a three mile long sandy wash that must be driven on to be believed. The lower canyon must be accessed by a series of stairways and ladders, and doesn't have the beams of light. But you park right next to the entrance and won't need to be shuttled. But it is my favorite for a different reason: the serenity. We've been herded like cattle in the upper canyon, shoulder to shoulder with hundreds of other people. On our tour of Lower Antelope, we felt like we were the only people in the canyon (and we may very well have been).

By definition there isn't a lot of water in Antelope Canyon most of the time. It's a desert after all. The water comes during cloudbursts in the watershed upstream. The flash floods will send fast-moving slurry mixes of sand, mud, and boulders through the bottom of the canyon. Tours aren't held if there is a chance of thunderstorms in the canyons above. Tourists have been killed and injured in the past, and safety is a priority these days.

Simple geology, but a work of natural art. Enjoy the photos that follow, and look to the end of today's post for a special treat...

The flute player in the first picture? He played a beautiful composition that echoed off the glowing cliffs. I'm hoping he has some appreciation for the beauty he brought to our day. Here's a portion for your enjoyment!

There were other parts to this beautiful day. I'd show pictures of Horseshoe Bend, but I'm afraid I was grocery shopping while the crew hiked to see it (that's something that happens when you are the leader of a trip). Here is a post from last year's visit to the incredible entrenched meander...

I recalled the Navajo Beauty Way prayer...

With beauty may I walk.
With beauty before me, may I walk.
With beauty behind me, may I walk.
With beauty above me, may I walk.
With beauty below me, may I walk.
With beauty around me, may I walk.
It is finished in beauty.
It is finished in beauty.

I've seen the beginning...

I'm no adrenaline junkie. When I've been at Disneyland, Splash Mountain and the Pirates of the Caribbean is about my limit. I was dragged kicking and screaming into Space Mountain, and came out also screaming, with rubbery legs. Roller coasters unhinge me. So what the hell am I doing, and why?

A few weeks ago I wrote about whether it is the journey or the destination that is important. And it is indeed the journey that is important. I've been to the starting point...

And I've been to the ending point...twice (below). But in-between those two points are 220 miles of wild river. I'm about to go down the Colorado River through the Grand Canyon for the first time in my life, spending 16 days to get from Lees Ferry to Diamond Creek. It's both a life-long dream, and just a bit mysterious and scary. The rapids are legendary. There are rumors of stunning beauty and spiritual discovery. There are groovers (don't ask). And I've come to realize that I am (re)learning just what it is like to be one of my students going on a long field studies trip for the first time, being shaken out of the every-day grind and opening up to the possibility of new and incredible experiences.

I am a rank amateur at rafting, so I've been trying to learn everything I can about trips down the Grand Canyon. I have the questions. Am I in good enough shape? Am I going to embarrass myself on the first rapid? What's it like to get dumped into the river? One thing I do know, though. I'm going to live every moment on the river. The sights, the smells, the sounds. So many of my travels have been wrapped up in organizing the logistics, dealing with student problems, keeping schedules and appointments, and making sure that everything goes somehow smoothly for everyone. On Sunday, I become a student once again, both in learning, and in responsibility. I won't be the one leading, I'll be the follower (and the chore-doer; no more of that managerial supervising crap!).

Like I said, I'm not an adrenaline junkie. I'm not too sure how I feel about running the legendary rapids like Crystal, Hance or Lava Falls. But it's the only way to see the heart of the Grand Canyon. I've been all over the rims, and I've been down (and up) four different trails to the river. But I've never been able to explore the river itself, or any of the side canyons that make such river trips so memorable. I'm looking forward to exploring as much as I can.

I am, I admit, an internet junkie, and tech addict. I'm wondering how I will survive 16 days out of contact with the cyber-world. Without my smartphone. Without my laptop. Then again, I hear there is this stuff called paper, and things called pencils and chalk. I'm told I can preserve memories and experiences on beaten wood pulp, so I may give that a try. When I return, I'll see about transferring the paper data to a digital format, and let you know how things turned out.

I won't be totally bereft of technology. I've got two nearly worn-out digital cameras that I'll be taking along. I figure at least one might survive the journey.

It's all the in-between I don't know so much about...

But maybe most of all, I'm looking forward to the time I'm going to have with my brother, my sister-in-law, and my two nephews. Their hard effort navigating the whole permit and organizational maze made this adventure possible, and they invited me along to share in it. I don't know if I can ever repay the kindness. It's going to be a grand adventure!

I might get a few more posts up before I leave, but then Geotripper goes dark for three weeks.

This month's Accretionary Wedge, sponsored by Evelyn Mervine at Georneys, is on the subject of geology-related signs. The subject is a good one, and it rang a little bell in my memory circuits; I remembered doing something on signs a LONG time ago, during the early Mesozoic era of geo-blogging, circa 2008. I did a little digging and came up with this post from March 6, 2008 (only two months after starting Geotripper):

Soon after posting a few death-defying pictures, Julian at Harmonic Tremors posted an additional photo of an "Unsafe Rock Area" (Danger danger danger! ), which brought to mind two of my favorite geology-related caution signs...the picture above is a sign warning of falling rocks at the base of a 400 foot "cliff" in southern England called Salisbury Cathedral!

The other sign may be familiar to travelers at Hawaii Volcanoes National Park. Just in case anyone feels uncomfortable passing such a sign, the park was kind enough to announce....

2013 addendum: I later found out that the "fault zone" in question suddenly split open a decade or two ago (in front of a geologist), and a short episode of lava extrusion and flow ensued. Then it stopped and has been quiet since.

I'm on the verge of one of my great life adventures. Sunday morning, I'll be rolling over the Paria Riffles (below) on the first day of a 226 mile journey down the Colorado River through the Grand Canyon. I've never done it, and I've always wanted to, and after 40 years of waiting, it's happening. I'm excited to have the chance to explore the depths of the canyon pretty much for the first time. I've hiked to the river on three or four occasions, at Hance Creek and Bright Angel Creek, but those trips were decades ago, and had little to do with the river itself.

Of course, there is no communicating with the outside world, so Geotripper will be on hiatus for a couple of weeks. If you are new to this blog, this is a great chance to catch up on some of the past Geotripper series on the Colorado Plateau, the Sierra Nevada, and other wonderful parts of the world. They're listed below...

See you all in a few weeks! With pictures, I hope, assuming I don't drop the camera in the river!

The Other California: what to see when you've seen all the really famous places in the Golden State (in progress).

Vagabonding Across the 39th Parallel: A journey through the geological wonderland in central Nevada, Utah and Colorado in 2011.

A Convergence of Wonders, a compilation of posts on our journey through the Pacific Northwest and Northern Rocky Mountains in 2011.

The Abandoned Lands, a compilation of posts on our journey around the margins of the Colorado Plateau in 2012.

Time Beyond Imagining: A "Brief" History of the Colorado Plateau - this was an extended exploration of the geology of one of the great geological showplaces on planet Earth

Under the Volcano and Into the Abyss: Yosemite National Park - Exploring a few of the lesser known corners of Yosemite Valley, from below and from above

The Airliner Chronicles: My First Blog Series - Seeing geology from the perspective of seven miles above.

Nankoweap granaries, built by the Ancestral Puebloans around 900 years ago

Well, I did it. I made the trip I've waited most of my life to do, and I had an incredible experience. The Grand Canyon is almost indescribable, although you know I'll try to do so over the next few weeks and months. There were something like 160 rapids, and I rafted 158 of them. I wasn't so lucky on the other two, and that will be a couple of the stories. I was unhurt, though, and today I am as happy as can be that I've finally been through the heart of the Grandest Canyon.

Redwall Cavern in Marble Canyon, Grand Canyon National Park

We are now ready to start on our way down the Great Unknown...We are three quarters of a mile in the depths of the earth...We have an unknown distance yet to run, an unknow river yet to explore. What falls there are, we know not; what rocks beset the channel, we know not; what walls rise over the river, we know not.

John Wesley Powell, on the Colorado River in Grand Canyon, August 13, 1869

The Great Unknown. In 1869, all of the contiguous United States had been mapped and explored, except for one huge area centered around what is now Utah, western Colorado and northern Arizona. All that was really known was that a few major desert rivers entered the region, especially the Green River, and the Grand, and that there was a place called the Grand Canyon and Grand Wash Cliffs where the river emerged. A few Native Americans lived within the region, of course, but they often didn't count in history, and their knowledge of the landscape was more local than regional. John Wesley Powell and his team of explorers made an epic journey down the river in 1869 and put the Colorado River and its canyons on the map. It was a seminal event in American geological research as well, serving as a springboard for a new understanding of geological processes and history. It was one of the last great geographical adventures in the lower 48.

When I was a young man, I was enthralled by the writings of Edward Abbey and others who knew and loved this mostly desert landscape. I was especially influenced by a wonderful book called On the Loose by Terry and Renny Russell, who in beautiful script distilled the essence of the land they loved into short paragraphs punctuated by what they thought were substandard photographs (they were wrong). I wanted, more than almost anything else, to explore the Colorado Plateau.

I walked the Paria River as a Boy Scout in 1974, and we emerged after a week at Lees Ferry, where rafting parties begin their Grand Canyon adventures. Two years later, as a community college student seeking a career direction, I participated in a week-long geology field trip into the Grand Canyon. We hiked down the New Hance Trail, spent a few days at Hance Rapids, and then climbed out along the Grandview Trail. The experience turned me into a geologist, and determined the eventual trajectory of my life and career.

Over the years I hiked down the main tourist corridors to Phantom Ranch a few times, and last year I drove down the Diamond Creek Road to the Colorado River, the main take-out point for river rafting parties. By age 56, despite dozens of visits to Grand Canyon National Park, I had witnessed only four points along the Colorado River: the take-in, a rapid, Phantom Ranch, and the take-out. And I was quickly reaching the point in life where a grand adventure like a rugged rafting trip might become physically impossible (I may have many years left of good health, of course, but one can never know).

And then, metaphorical lightning struck. On a whim (and at the suggestion of a rafting acquaintance) my brother Mark had applied for a highly coveted permit to conduct a private raft trip on the Colorado River. Many people wait for years to get one, so it was a great surprise when he got a letter saying he was the permit holder for a 16 day trip with 16 travelers. The problem was that he knew little about river rafting, so his friend set out to gather a team of rafters who could accommodate my brother's family and organize the complicated logistics. When all was said and done, there was one space left on the rafts. And my dear brother offered it me. I said yes.

So three weeks ago I found myself standing on the riverbank at Lee's Ferry, watching the rafters preparing their rigs, and anxiously wondering what lay ahead. Most of the oarsmen had been down the river many times, but I was facing my very own Great Unknown. As I've mentioned before, I am no adrenaline junkie, so I wasn't there for a joyride down the famous and infamous rapids (though I learned to love...um...most of them). I was there to learn about the river and landscape it flowed through, and even though it has become a cliche of sorts, I was there to discover something about myself. I was stepping way outside of my comfort zone, something I haven't done much over the last few decades.

There I was, standing on the muddy bank of the Colorado River, ready to embark on the grand journey. It was a mess of feelings: apprehension, trepidation, anxiety, but most of all, excitement and anticipation. Just imagine what it is like to be just minutes away from starting a journey you've waited 40 years to undertake!

I now have two stories/blog series in process, the Great Unknown, and America's Never Never. They belong together, the later being the exploration of the land eroded by the Colorado River, and the former the journey on the river itself. I will jump back and forth between the two. Some blogging may be spotty, as school is starting up very soon, but I'm looking forward to sharing the story!

Before we embark on our journey down the Colorado River, I wanted to discuss an aspect not always mentioned by adventurers and thrill-seekers: environmental protection of the river. Environmentalism is far too often attacked as some sort of elitist Marxist plan to make life difficult for corporate air and water polluters, but it is in the most elemental sense an attitude to keep our world liveable for the people and animals who are its inhabitants. Why foul the only nest we have?

We see this in microcosm on the Colorado River. There is the river itself, and the numerous animals and plants it supports that must be protected, but at the same time, the rafters and hikers who explore the river need protection too. Getting sick on the river is no picnic. Not only that, how fun can a river trip be if the camps every night are trashed up, with the threat of stepping on human feces every time you wander the edge of camp? Ever since the spillways of Glen Canyon Dam closed in 1963, the sandy beach camps of the river have been eroding away. In two hundred miles of river, there aren't more than 100 or so possible camps, and 800+ people will be spread out in these camps each night. The campsites have to be cared for.

So what is it like to practice lowest-impact camping?

It means that you start a trip with all the food and materials you need to live for 16+ days, and you bring everything out of the canyon at the end (transformed in some cases into a different kind of material...). You give constant thought to hygiene as well, because as pristine as the wilderness is, the river is not. The tributaries of the Colorado River upstream drain thousands of square miles, and dangerous pathogens are already present in the water (especially when the Page, Arizona water-treatment plant overflows during monsoon storms).

The rafts in our group were mostly about 16 feet long, and look like the simple pontoon boats one would use on a day trip, but these are made of tougher material (despite all the scratches and collisions with rocks, there was not a single leak on any of the boats during our trip). They are fitted with an aluminum framework (rigging) that provides the anchor points for carrying ice chests, dry boxes, waste cans, and the all-important oarlocks. They also provide seating (riding on the pontoons in a rapid is not generally a good idea). As a rule, ice chests and dryboxes never leave the rafts for the duration of the trip. When dinner prep is going on, the cook crew goes "shopping", getting the food items they need from each raft (there is a master list to follow; the cold food is highly organized because the ice chests need to be opened as little as possible. The ice has to last the whole trip!).

When we pulled ashore in camp, one of two things happened. If the day had been relatively placid, we immediately unloaded the kitchen gear and personal luggage. If it had been a trying day, we invoked the one-beer-rule, a few moments when a can of something was consumed quietly.

Once the gear was onshore, buckets were filled with river water. The Colorado carries an incredible amount of silt and clay, and the water can take all night to settle. We would add a few drops of a flocculating substance (hey, we had four chemistry professors on the trip), and the water would settle after an hour or so. This became the wash water (drinking/cooking water was carried in five-gallon containers; the flotilla had a capacity of 55 gallons, enough to last three or four days)

The day's cooking crew picked their campsites and then set up the kitchen. There were four aluminum tables, a strongbox with pots and utensils (a heavy monster), a four-burner propane stove, and the "rocket", a propane blaster the likes of which I've never seen before. It could boil a couple of gallons of water in minutes, and I suspect it could have gone airborne if inverted. And under it all, a nylon pad designed to catch errant bits of food. A hand-washing station was set up, and was used constantly.

What happens if bits of food get left on the ground? The red ants move in, and ant bites hurt like hell. They don't normally nest on the beaches, but they can be attracted there.

One night we spilled some uncooked rice grains, and a drama unfolded as an ant discovered the treasure and passed word. Within a few minutes the cook area was crawling with ants looking for more. We could easily follow the trail back to the nest.

If we were cooking steaks or using the dutch oven, we lit charcoal in a fire pan. The ashes were collected and added to the organic waste. Ashes can also pollute a campsite, as can fire rings. If you want a fire, you have to bring your own wood, although on off-season trips, you can burn driftwood, but only in the firepit. That's the very first cake I've ever baked, below, a German chocolate. I am relieved to say it came out okay!

After the efforts of the cook crew bore fruit (and meat, and vegetables, and dessert), we sat down to a feast. River menus are the stuff of legend, and ours was no exception. We enjoyed shrimp and linguini, salmon steaks, tri-tip, pork loin chops, chicken fajitas, rib-eye steaks, butternut squash ravioli, curry stew, jambalaya, and enchiladas, along with all manner of salads and vegetable sides. And the view from our restaurant was marvelous!

Breakfasts were equally tasty, with omelets, pancakes, french toast, and lox with bagels. Even cold cereal once or twice, on busy days.

Once the cooking was done and meal served, it was time for cleaning up. Although the cook crew was ostensibly responsible for cleaning up as well, most nights volunteers jumped in to help. The wash station, below, consisted of four buckets, one for washing off food particles, one for a hot soapy wash, a hot water rinse, and a soaking in a bleach solution. Dishes and utensils then air-dried in nylon bags attached to the tables and were then put away for the night. All dishwater was strained of food particles and dumped into the river. All food was put in strong boxes or back on the boats to keep the ringtail cats and various rodents from making a mess of things. The nylon pads were cleaned off in the river. All food waste was put into the large ammo cans and put on the rafts. Paper and metal waste was bagged and stored on the rafts as well. Ultimately and ideally, no food particles remained in camp when we left.

I was surprised and pleased to say that it worked. Not one of the camps we occupied had trash beyond the stray bit of paper (which we picked up). When we arrived after a rainfall, there was hardly a sign of human presence in the camp at all, not even footprints. For all I knew, we were the first to see these incredible places!

And finally, a word about the other part of environmental protection and personal hygiene. What did we do with human waste? Simple: liquid waste went straight into the river. That sounds terrible, but a flow of 10,000-15,000 cubic feet per second dilutes liquid waste very quickly, and if we did our business on land, it would not be washed away for weeks or months, all along attracting flies and other vermin.

Solid waste was trickier, but the system worked. What you see above is the handwashing station, and the "key", which you took with you when you went to do your business . That way, no one would interrupt you. All solid human waste and toilet paper went into the large watertight ammo cans called "groovers". They were called this because in the olden days of rafting, there was no toilet seat, so you had a pair of grooves on your posterior after doing your business. When an ammo can was filled, it was closed up very tight, and stored on a raft. It would not be dealt with again until we offloaded at the end of the trip (I'm happy to say that the company we rented these from did the cleanup).

The system worked, and the river and camps remained protected from raw human sewage. When we were loading up the rafts in the morning, someone would ask if we were all "groovy" so they could take the toilet down. It was a bit of trouble to use the system, but I wouldn't have it any other way.

One positive aspect: the groover site was chosen as to have the most dramatic vista possible. The view was almost always inspiring.

And that's how we did it. Coming up next: what I saw on the river!

It was time to begin our journey down the Colorado River, or as John Wesley Powell put it, going down the "Great Unknown". In his day, no one had been down the river. But since Powell's epic trip in 1869, a half million people have made the journey, and there is an entire library of books, maps and guides describing each rapid and eddy in the river. Today the river is "known".

But to me it was still the "Great Unknown". To someone with absolutely no whitewater rafting experience, the Colorado River might as well have been on Mars. Book knowledge is helpful in setting a frame of mind about traveling down the river, but preparing you for the experience? One might as well try to learn Judo from a book. I was quietly apprehensive as we drove north from Flagstaff towards the take-in at Lee's Ferry.

One doesn't exactly drive up and jump into a raft. With so much traffic on the river, there are regulations designed to space groups out, so a trip begins with an afternoon rigging, a night on the banks of the river, and a morning briefing and inspection by a National Park Service ranger. Once cleared by the ranger, the expedition can begin.

As we drove along, we couldn't help but notice the towering cumulus clouds ahead of us. The Arizona monsoons were in full flower, and it looked like we were going to have some serious rain activity.

We crossed Navajo Bridge just outside Lee's Ferry and stopped to have a look at the river, 470 feet below us. This brown water would be our home for the next 16 days. We watched another group float by, thinking how that would be us the next day. The river is calm in this stretch, but we could still see numerous eddies and upwellings that belied the apparent calmness of the river.

We arrived to find a flurry of activity as the rafters prepared their rigs. At this point there wasn't a lot to do except stand ready to hand over equipment and luggage, or fill water jugs. Oh, and cull down the stunning amount of stuff we had in our luggage. I pulled one item after another from the dry bags, and then pulled more, and when we handed them over to be loaded on the raft, they got lifted up, heavily, and eyes rolled. Rookies....

For future reference, Garry, you can get by nicely with perhaps half the stuff you brought this time.

The first storm hit with a vengeance. I was surprised for a moment that no one seemed upset that their stuff was getting all wet. And then I remembered that everything we had was expected to get wet. We were going down a white-water river after all. I took my camera and other sensitive stuff to the big shade structure to wait out the storm.

This storm was big. One maybe needs to understand that I come from California's Central Valley where we get maybe one or two thunderstorms a year, but even our Arizona travelers were impressed with the downfall, the thunder, and the wind, which sent raindrops hurtling sideways. Within minutes there were dozens of waterfalls coming off the cliffs around us.

We would not know it for two weeks, but the series of storms around the beginning of our trip caused havoc in the region. Check out this video of the simply unbelievable flooding at Antelope Canyon and Page, Arizona that took place during these few days. Antelope is a slot canyon 50-100 feet deep, and it was filled over the brim. We would also see side canyons downstream forever changed by debris flows.

For us, the storms brought about beautiful waterfalls, and being the first rainfall of the season at Lee's Ferry, also brought out a veritable zoo of toads, frogs, lizards and bugs along the river. A beaver swam by (I finally realized why saplings around the riverbank had wire mesh wrapped around them).

The storm eventually subsided, and we made our first boat journey...150 yards downstream to the river camp. We set up tents (expecting more rain), and drove down to Cliff Dwellers Lodge for dinner. The night was cool and humid, in sharp contrast to the sweltering August temperatures I was expecting. There was even mist rising on the river (see the picture in this post). I slept...okay.

The morning included an impossibly beautiful calm river with the brilliant Vermilion Cliffs in the distance. The cloud cover promised rain, however. We packed our gear, loaded the rafts, and rowed back to the take-in for the ranger briefing. Once could tell the veterans from the rookies at the briefing: the veterans looked like glassy-eyed airline passengers sleeping through the emergency procedures, while the rookies like me hung on every word with widening and fearful eyes. Scorpions? Rattlesnakes? Deadly Rapids? Flips and upsets? Norovirus? Wait, what the heck is Norovirus? Ah, the reason (among many) for the almost OCD-like compulsion to wash hands over and over in camp. What could be worse than a highly contagious intense gastrointestinal disease spreading through camp, short of broken limbs or death?

As the ranger finished her briefing (it wasn't really brief, by the way), the second massive cloudburst hit. It was more intense than the first, and within a few minutes the insignificant drainage next to the take-in was flash flooding. In the picture below, you are only seeing the overflow portion. I could hear cobbles bouncing along the streambed in the main current. A couple of kayakers couldn't resist playing in the surf.

Once again we retreated to the shade structure and waited out the storm. When it cleared, we were clear, too. Clear to go.

I donned my lifejacket, had a "before" portrait taken, and we took our places on the rafts. I was the sole passenger on Pete's 15-foot NRS self-bailing raft (self bailing is a wonderful feature). Pete is a professor at a small college where he is now a dean, but he also teaches a class in literature of the outdoors. He also has a farm. And to my delight, I found out he had brought along a guitar and collection of harmonicas.

We determined the order of the six rafts (we were to be last, as we carried the biggest first aid kit), and one by one the boats were pushed off, and our journey had officially begun.

At that was that. With a last look toward the loading area at Lee's Ferry, we left behind all trappings of civilization for the next week. We would have no contact with society until we reached Phantom Ranch in the depths of the Grand Canyon in 8 days or so.

When we pushed the rafts off the beach at Lee's Ferry, my normal sense of time disappeared. For my journey into the Great Unknown, I didn't have a watch, and my smartphone was safely ensconced in one of the vehicles. My laptop never made it beyond Phoenix. Time took on a new meaning.

There was river time. That one is controlled by the sun, mostly. There was twilight and dawn, which guided when one went to bed, or arose. There was star time, the sweep of the Milky Way that told you the stage of the nighttime you had awakened in. There was worst sun time, the baking hot part of the day that often guided the choice of lunch spots. And there was afternoon shadows time, that told us it was time to pick a campsite.

Then there was geology time. As we descended through the first 80 miles of our river journey, we weren't just following the flow of the river downhill, but were also making our way back in geologic time. As the canyon deepened (or as the cliffs rose higher around us), we were encountering a sequence of successively older and older rocks. The youngest rocks, about 250 million years old, were exposed at Lee's Ferry, and at Mile 80 we would encounter some of the oldest rocks in the canyon, at 1.7-1.8 billion years.

As we started down the river, there were still small waterfalls tumbling off the cliffs, courtesy of the just-ended cloudburst. I was especially entranced by the double fall at Mile 4, which was trickling over ledges of the Kaibab and Toroweap formations. The Kaibab, which is familiar to all visitors at Grand Canyon National Park, forms the rim of the Grand Canyon. It is a sandy limestone that formed in a tropical shallow marine environment that developed at a time when the supercontinent Pangea had come together. The Toroweap Formation is broadly similar to the Kaibab, but is a limey sandstone. The difference might not mean much to non-geologists, but it means much to geologists who are interpreting the environment in which the rock formed. Where the Kaibab formed in offshore shoals and reefs, the Toroweap formed along the sandy coastline. Both formations are highly variable and the Kaibab especially has a rich fossil record, including corals, bryozoans, sponges, clams, gastropods (snails), and the occasional shark tooth.

Within a few million years, 90% or more of the species found as fossils in these rocks (and all other rocks worldwide) would be gone in the greatest extinction event of all geologic history. This event did not involve the dinosaurs; instead, it quite possibly made it possible for the dinosaurs to evolve and rise to dominance in terrestrial environments.

We would see the Kaibab and Toroweap formations at river level for less than 4 miles. They would be visible at times during the rest of the trip, but only as remote cliffs as much as a mile above us. At Mile 4, under another trickling waterfall (below), we crossed the contact between the Toroweap Formation, and dropped into exposures of the Coconino Sandstone. We passed beneath the Navajo Bridges at Mile 4.5, and I knew suddenly that we were indeed beyond all parts of the Colorado River with which I had any familiarity.

The Coconino Sandstone is an extraordinary rock unit. It has a distinctive pattern of crossbedding, a sort of diagonal layer formed as sand cascaded down the slipface of a sand dune. The crossbedding can be seen above just over the river vegetation. It formed in early Permian time as sand dune “sea” in a desert that extended across northern Arizona, New Mexico and southern Utah and extending north as far as present-day Montana. The Coconino preserves more than two dozen kinds of tracks, from large amphibians or reptiles to scorpions or spiders. We didn't see any of them because the Coconino was exposed along the river for only about a mile, and we weren't ready to stop yet.

By Mile 5, we had reached the contact of the Coconino with the underlying Hermit Formation (or Hermit Shale as I learned it). The Hermit is a bright red-brown formation composed primarily of silt and shale that formed in the coastal floodplains of an extensive river system. The rivers were coming from somewhere geologically special, but I'll have to save that for our next post. The Hermit was just the tail end of an important geological event in the region during late Paleozoic time.

People can be forgiven for thinking that the Colorado River carved the Grand Canyon. That's true in one sense, but a river can generally only cut downwards, and it cannot account of the vast breadth of the tributaries and side canyons. Once a steep gorge has been carved, instabilities are introduced (i.e. oversteepening of slopes) that leads to mass wasting, in other words, landsliding. Much of the canyon has been produced by a combination of landslides and debris flows/flash floods. We passed numerous examples in the first days of the trip, including the spectacular rockfall consisting of Kaibab, Toroweap and Coconino rocks in the picture below (to the right).

The storm damage was catching up to us as well. Not a tree was visible from Lee's Ferry or on the surrounding cliffs, but as the day progressed, the river became nearly choked with branches, cones and seeds from juniper, pinyon and other trees that grew at the upper end of the Paria River and other tributaries. We didn't have to bail the self-bailing rafts, but I often had to grab handfuls of debris from the boat after getting splashed in a few rapids.

A bit further down the river we saw another recent rockfall...

And at the ten mile mark, we passed the imaginatively named Tenmile Rock, a huge slab of Coconino Sandstone that broke away from the cliff, tumbled down the slope, and landed in the river without quite falling over flat.

It was huge!

The rapids the first day were an introduction to a pattern that would continue throughout the trip. The river flowed placidly through the canyon until we reached a tributary drainage. Debris flows emanating from these side canyons burst into the main channel, partly damming the channel, and pushing the main flow of the Colorado River to one side or another. With the constriction, the river would speed up, and smooth undulations would develop in the top of the rapid, forming a "vee" pointing downstream. The vee was bounded by lateral waves, and at some point the rower would either punch through the laterals (especially in the biggest rapids), or follow through the roller coaster of big waves in the center of the channel.

A series of eddies would form at the base of the rapid (literally a large whirlpool flowing partly upstream), allowing the first boats down a chance to take position in anticipation of assisting anyone ejected from a boat in the midst of the rapid.

The seriously big rapids had special problems, including pour-overs, holes, and exposed boulders that needed to be avoided at all costs. When approaching such rapids, the rowers would pull out, and climb to a vantage point that offered a chance to scout the rapid. A discussion of the best possible run would ensue, and the bigger the rapid, the longer the discussion (and for the rookies, increasing apprehension). An order was picked for the boats and off we would go.

Our first day included two riffles, Paria and Brown, rated 1 or 2 out of 10 on the Colorado Rapids classification system. We also were baptized by two class 5 rapids, Badger and Soap Creek. One thing became abundantly clear: don't take a Colorado River rafting trip if you hate getting wet. Literally every rapid would find a way to douse the passengers in the front of the raft. Mind you, when the temperatures were high, it was a welcome relief, and I generally looked forward to getting soaked! Even the smallest rapids could surprise; we found out later on that a boat flipped in the Paria Riffles a day or two after we came through.

You will also notice that I have few pictures of the rapids. My camera and silty, muddy water don't mix well, so when I heard the roar of a rapid coming up, I would snap a shot or two of rafts going over the edge, and when we got safely to the bottom I would pull the camera out and try to snap a shot or two looking back upstream, such as in the picture above at Soap Creek Rapid.

Our first day, we managed (after the late start) a modest 12.4 miles. We stayed that night at 12.4 Mile Camp (where do they come up with these creative names?). It was a cool evening because of the cloud cover. We knew hotter days would come, so we enjoyed the moderate temperatures. I set up camp, and after a dinner of fresh shrimp and linguini, I hit the sack.

Coming up next: the Roaring Twenties!

The new day, our second on the grand river, began with a startling sunrise. Sunrises and sunsets in the Grand Canyon are not like other places. One never sees the sun rise above or dip below the horizon, because in the deep canyons, there is no such thing as a horizon. Like Plato's cave, we can only comprehend the sun rising over the Earth's horizon by imagining it from the reflections coming off the adjacent cliffs. If the sun hits camp at sunrise or sunset, someone has made a big miscalculation in choosing a campsite. Staying out of the sun for as long as possible is a continuing strategy during a summer rafting trip on the Colorado.

There was a foreshadowing of today's mystery in the previous post. On our continuing journey into the Great Unknown, rafting the Colorado River through the Grand Canyon, we had passed through three geological formations, the Kaibab, the Toroweap, and Coconino. The first two formed in a coastal environment, while the Coconino developed in a sand dune dominated desert. But we ended our first day on the river in the midst of the Hermit Formation, a striking red-brown layer composed of siltstone and mudstone. The bright red color in such rocks (and the presence of sedimentary structures like ripplemarks) is strongly indicative of deposition in a river floodplain environment.

As we drew deeper into the canyon, we encountered successively older rocks, and they revealed more and more redbeds. Now there were ledges and cliffs of sandstone and other coarser sediments, indicative of a higher energy environment, such as the river channels of large floodplains and desert sand dunes. Clearly a major geologic event had taken place, one that produced a vast volume of sediments over a wide region. For a region of the Earth's crust that had remained remarkably stable for nearly a billion years, this event stood out.

We had entered the Supai Gorge, named for the four formations of the Pennsylvanian-Permian aged Supai Group. Their names are tongue-twisters: the Watahomigi, Manakacha, and Wescogameformations and the EsplanadeSandstone. Where did all these sediments come from, and how do we know? The sediments had to come from a mountain range, but any such mountain ranges no longer exist, having been eroded to rubble many millions of years ago.

Ripplemarks and crossbedding in the sediments show that the rivers were flowing in a general southwest (today's southwest, anyway) direction, meaning the mountains lay to the east or northeast. In southwest Colorado, there are younger rocks, similar to the Mesozoic rocks found around Zion and Capitol Reef in southern Utah. But beneath them where the Paleozoic rocks should be found, there are only ancient Proterozoic metamorphic rocks and intruded granites. These ancient rocks are the roots of the Uncompahgre Uplift, otherwise known as the Ancestral Rocky Mountains.

The origin of the Ancestral Rockies remains somewhat of an enigma to geologists. They coincide in time with the collision of South America and Africa with the southeastern part of North America, an event that ultimately produced the supercontinent Pangea. But the Ancestral Rockies are hundreds of miles removed from the collision zone, so geologists infer a sort of chain reaction in the crust along ancient fault systems. In any case, the rise and destruction of a mountain range in Pennsylvanian and Permian time has provided us today with one of the most scenic and colorful layers in the Grand Canyon.

I came to love two bird species who make their home in the canyon. One of them was the blue heron. We would see them all through the canyon, gracefully soaring over the water, or stepping carefully in the shallows, looking for fish and other prey.

We continued to descend deeper into the canyon. Today's route would take us through a part of the canyon called the "Roaring Twenties", a series of rapids spaced on average only a half mile apart. After the relative paucity of rapids on the previous day, it was a real roller coaster. Remembering the scale of 1 to 10 for rapids in the Grand Canyon, we faced House Rock Rapid (7), North Canyon Rapid (5), Twentyone Mile Rapid (5), Twentythree Mile Rapid (4), Twentythree and One-Half Rapid (4), Georgie Rapid (6), Twentyfour and One-Half Rapid (6), Twentyfive Mile Rapid (6), Cave Springs Rapid (5), Tiger Wash Rapid (5), and Twentynine Mile Rapid (2).

All the boats made it through the rapids without incident, until (I think) Tiger Wash. As we slipped over the tongue of the rapid, I thought I saw one of the boats go vertical, and someone tumbled out. I thought it was my nephew at first, but soon found that it was the boat with my brother and his wife. Somehow they had stayed in the boat, but unbeknownst to them, their oarsman was missing. They heard him say something along the lines of "your oarsman is NOT in the boat". They looked behind in surprise as he clawed his way back onto the raft just in time to get hung up on a boulder. Our raft was closest, so Pete rowed back into the eddy, and we started to climb up the rocks to see if we could assist, but they managed to back off the rock, and we were able to continue on.

Looking up the canyon, we could see that the monsoon storms were not finished. The towering cumulus clouds were wreaking havoc upstream, but the day remained sunny and clear for us. Tonight I would be sleeping under the stars.

We passed another stunning example of mass wasting just before hitting the Roaring Twenties. Boulder Narrows is a huge single chunk of Esplanade Sandstone that practically dams the river (below). According to the river guide, it is the single largest boulder to be found in the river through the Grand Canyon.

The canyon became deeper and more vertical.

At lunch, I was able to concentrate on smaller things, like the wonderfully colored and patterned river boulders.

The Supai Group is one of the thickest units in the Grand Canyon sequence at more than a thousand feet, so it was with us for quite a few miles. I had not been this close to the redbeds in a long time, and the ledges and cliffs made for a scenic stretch along the river. The combination of scenery, geology and rapids made for a memorable day.

There was an otherworldly appearance to the cliffs that rose above us, straight out of the river.

At mile 23, a new layer appeared, hard ledges of gray limestone. We had reached the Mississippian-aged Redwall Limestone. There wasn't a bit of red in it, at first, but that would change before long. I'll save the detailed description for the next post, because today's exposures were just a preliminary tease.

The Redwall Limestone is a true cliff-forming rock, and in places the rock hung over the river.

After the excitement of eleven major rapids and a near miss in the flip department, Pete was a bit tired. We were past the rapids of the Roaring Twenties, so I took to the oars for a couple of miles. I'm not saying I'm a natural oarsman, but the several miles I rowed probably amounted to about a half mile of actual river. I had a devil of a time sticking with the current and staying out of the eddies. Plus, you can see I didn't put on my gloves, so I also got a blister (whine, whine). It was fun!

In the next post: the incredible Redwall Limestone of Marble Canyon.

The third day of our journey down the Colorado River began as an idyllic journey through paradise. If that seems like a set-up for a disaster at the end of the day, it isn't, unless you count the poor bug (read below). We were traveling about 12 miles from Shinumo Wash to Lower Buck Farm Camp, a stretch of river remarkably free of large rapids (Thirtysix Mile Rapid, a 4, was about it). We were well into Marble Canyon, where the river walls are dominated by the Redwall Limestone (not really marble, but the river polish makes it look like marble). To me, the day was as close as I can imagine to being an earthly paradise: full of beauty, color and serenity.

The Redwall Limestone had its origin in a sort of serenity, or maybe stability is the better word. For millions of years during the Mississippian Period, between about 360 and 323 million years ago, a shallow tropical sea spread and regressed across the continental interior. The tropical waters were filled with life, including crinoids (sea lilies), brachiopods, bryozoans, clams, snails, fish, sharks, and even a few trilobites. It accumulated to depths of 400 to 800 feet, and the hard limestone forms one of the most prominent cliffs in the Grand Canyon (the location of practically every trail in Grand Canyon is determined by where it can cross the Redwall).

Limestone dissolves in mildly acidic water, so caverns will form readily in the Redwall. A vast network of caves are present throughout the Redwall, and many open out into the cliffs above the river. Being an armchair spelunker, I wanted to get out and find a way to explore every cave we saw in the cliffs above. Most were clearly inaccessible, but the cave in the photo above could be reached by humans. It was used by Robert Brewster Stanton in 1889 to stow some of their gear as they abandoned their tragic journey down the river after their leader (and bankroller) and two others drowned. It is called Stanton's Cave to this day.

It turns out, though, that humans have used the cave for a long time. 3,000 to 4,000 years ago, humans constructed split twig figurines, and left them in Stanton's Cave by the dozens. It is thought that 165 of these precious archaeological treasures were removed by visitors between 1934 and 1969 before the park service removed the remaining 74 during an excavation (my feelings about this looting is unmentionable in this family-rated blog).

Split twig figurines on display at Tusayan Ruins, South Rim of Grand Canyon National Park

Other creatures used the cave as well, including California Condors and Mountain Goats, whose dated remains go back 12,000 years. And remarkably, driftwood was carried into the cave during a river flood around 40,000 years ago. The cave is 160 feet above the river!

Most recently, the cave has been occupied by several species of bats, including the rare Townsends big-eared bat. The largest nesting colony known in Arizona was present here years ago, but persistent tourist incursions drove them away. Eventually a gate was constructed to allow access for the bats, but to keep people out. Apparently it has been working, and a colony has been re-established.

Just downstream of Stanton's Cave, an expected splash of greenery coated the slopes of the canyon before us. As we drew closer, we could see water bursting out of the cliffs. Water is another wonderful property of the Redwall. The caverns, fractures, and fissures provide avenues for groundwater percolating through the layers above to be concentrated near the base of the formation, and springs are a common feature at the base of Redwall Formation. Vasey's Paradise was a wondrous example of one of these springs.

We pulled out to have a closer look (for some it was an opportunity to fill their solar showers with clear spring water). We had to step carefully, because some of the greenery was composed of poison ivy!

I caught a shot of my brother enjoying a view from a large boulder along the shoreline. I carefully made my way down to join him. Carefully, because only a week before the trip I had done something to my heel and even had to use a cane for a day or two to get around. I didn't want a recurrence, and was only wearing sandals while on the river. The rock provided a nice upstream perspective of the springs.

Back on the river, we passed another Blue Heron. I couldn't resist another few pictures!

After another few bends in the river, I got a lesson in perceived scale. One can see a dark cavern at river level in the distance. As we got closer the hole got bigger...and bigger...and bigger! We had reached Redwall Cavern, one of the more extraordinary sights on an extraordinary river. John Wesley Powell remarked in 1869 that the huge declivity could hold fifty thousand people. Others later suggested more like 5,000, but in any case, it is huge. We pulled out for a little exploration.

Even before turning my camera into the cavern itself, I had to snap a shot or two of the reflections of the surrounding cliffs on the river. This was one of the calmest parts of the river so far, but Redwall Cavern must exist in part because of lateral erosion of the river during high water (the entire cave was filled with water in 1957 during a flow of 122,000 cubic feet per second; today's flow was more like 12,000 cfs).

Blocks of Redwall that had fallen into the cave contained numerous fossils. Some of our travelers pointed out the crinoids and brachiopods seen below.

I started exploring the depths of the cavern, taking the surprisingly long walk around the back of declivity. The scale is impressive, compared to the rafts of our little flotilla.

The ceiling of the cavern provides a nice frame for looking at the river.

Did I mention that the cavern is huge?

It was a fascinating place to wander, and a cool respite from the sun. I've also seen video of Redwall Cavern in an entirely different circumstance; check out this example of the cavern during an intense monsoon storm. It's awe-inspiring...

Ichnology is the study of trace fossils, the tracks, burrows and other traces of past life in the absence of shells or bone. I've seen many trackways in ancient sandstone formations, but we saw a bit of drama reflected in the sand within the depths of Redwall Cavern. A large beetle had been walking along the uneven sandy surface, and had come to grief in someone's footprint. Such dramas have been preserved in formations like the Coconino or Supai, and in the right conditions, the same could have happened here. The story has a happy ending; the beetle wasn't dead yet, and we set him upright again to continue his journey.

The day continued, but this post is already long. To be continued!

What the heck? Read on to solve this little mystery..

Our adventure in the Great Unknown of the Colorado River continued through Marble Canyon. We started the day with stops at Vasey's Paradise and Redwall Cavern (in the previous post) and now we were floating down a canyon with 500 foot sheer walls. Here and there, water trickled from springs in the Redwall Limestone, and at several of them seeds had found a place to root (below).

About two miles below Redwall Cavern we made a stop at another well-visited site: Nautiloid Canyon. Nautiloids were relatives of the octopods, and can be thought of as octopi with shells, some of which were coiled like a snail, or straight, like a long thin cone. Three species exist today, including the chambered nautilus, a common sight in curio shops. At times the nautiloids dominated the seas, especially during the Mesozoic Era (the "age of dinosaurs"). In Nautiloid Canyon, a number of them have been exposed by the erosion and polishing of the Redwall Limestone.

To see them, we needed to climb 75 feet up a limestone ledge and head into a slot canyon. They are easier to see when wet, so one of the party can be seen hauling a bucket up the rocks.

Before heading into the narrows, I stopped and took a look at the canyon below us. I wondered, here on the third day of our trip, if I would get tired of being inside these canyon walls at some point in the next thirteen days (for the record I never did!).

Marble Canyon is sometimes thought of as a sort of preliminary introduction to the "real" Grand Canyon. I found it to be one of the most beautiful canyons I had ever laid eyes on.

The nautiloids were quite fun to see (a two foot long shell is just left of center in the picture below), but in searching for shade, I noticed something else that I found very interesting.

As I've mentioned before, the Redwall Limestone is riddled with caverns. Looking at the waterfaull that blocked any further progress up the canyon, I noticed there was a large cavern opening in the shade on the left. I walked up to see if it contained any of the usual cave decorations like stalactities or stalagmites (these features are collectively called speleothems).

What I found in the openings above my head was a surprise: there was a lot of red dirt and debris. It wasn't much to look at, but it contained the beginnings of an answer to a question I've asked myself on occasion. Could a cavern exist for millions upon millions of years in the Earth's crust? Many of the caverns that exist in the world today are a few million years old at most, but I understood that the Redwall Limestone exhibited evidence of karst topography, the sinkholes and blind channels that develop as caves grow and collapse. The karst developed not long after the Redwall was deposited in Mississippian time.

The sinkholes and caves would fill with debris from above, some being carried by rivers and streams. A new formation was described in the 1970s, nearly a century after one would think all the formations had been discovered. Appropriately known as the Surprise Canyon Formation, it is composed of stream gravels and silt layers deposited within the karst openings of the Redwall in late Mississippian and early Pennsylvanian time. It was looking more and more like I was finally standing in the opening of a cave that existed before the age of the dinosaurs! It had been protected through the ages by the fill of dirt and gravel.

Now, about that weird looking feature in the opening photograph. We stopped for lunch at mile 35.3 and I was directed to have a look at these miniature "hoodoos" (or maybe it was the maw of tourist-eating space creature). It didn't take long to see what was happening.

They were pools in the loose sand below springs dripping out of the ferns up above.

After lunch, we continued a few more miles down the canyon, drifting in the gentle current and enjoying the view of the high canyon walls. Caves were everywhere.

We ran the one moderate rapid, Thirtysix Mile (4), without incident...

A mile or two later we stopped at one of the most ominous sights I had yet seen. In the 1950s, a dam was proposed to be built in Marble Canyon. They went so far as to drill exploratory tunnels to test the soundness of the limestone. I was appalled that anyone thought to dam this river, and as a geologist I really wondered at the sanity of trying to plug all the holes in the cavern-riddled Redwall Limestone. The reservoir would probably have leaked like a bathtub with dozens of drains.

We stopped and explored the tunnels. I didn't take a camera, but I was surprised at the length (and complexity) of the tunnels. In the greatest depths there were hundreds of stalactites growing from the cave ceiling. New flowstone was draped on the tunnel walls like white icing on the side of a cake. The new speleothems were pearly white, and the stalactities were about an inch long. I was witnessing the formation of a brand new cavern after exploring another that has existed for geological eras. It was a strange juxtaposition, and the tunnels a jarring contrast to the magic of the river. What insanity would allow a dam to be built here?

The last few miles to camp remain in my mind as some of the most pleasant moments of the entire journey. We floated down a calm river, and after a bit, Pete stopped rowing and leaned back. We drifted with the current, and after the brief sound of water dripping from the oars, it was silent. Shadows had fallen across the river and the high cliffs were reflected off the surface of the water.

It was one of the most beautiful moments I could imagine.

The Grand Canyon has many moods. So many of my pictures show a canyon bathed in bright sunlight and vivid colors, but twilight often revealed softer tones. The picture above is the view from my campsite at Buck Farm Creek at dusk on the third night of the trip.

We continued our journey into the Great Unknown of the Colorado River. On day four we were expecting to make for Nankoweap Creek about 11 miles downstream. For me it was the chance to find the "river" within the river. That's not some kind of philosophical quest. It was a geological thing, to be explained shortly. But before that, we did some exploring with the extra time afforded by a short distance on the river.

As we often did, we explored the area around our camp while taking advantage of the shade. We headed up Buck Farm Canyon just to see what could be seen. There were a lot of large fallen boulders of Redwall Limestone littering the lower slopes.

Buck Farm quickly narrowed as we climbed up the canyon. We had reached deeper into the crust and were now walking on ledges of Muav Limestone, which in most places underlies the Redwall Limestone. It seems simple to say that one layer sits on top of another, but there is just a bit of time difference between the two layers: the Muav dates from the late Cambrian Period, while the Redwall is Mississippian in age. More than 150 million years elapsed between the deposition of the two layers. That's the same time period that separates the Jurassic (and her many dinosaurs) and our own current era. What happened here?

We climbed over the dry talus slopes and eventually discovered a verdant canyon and even a small clear trickling stream. It was a nice little explore, but now the sun was shining down on us, furiously hot. We headed back to the river.

It was another day remarkably free of large rapids, with only President Harding Rapid (4) standing in our way. As we drifted down the river, more gigantic caverns could be seen in the Redwall cliffs. I think the alcove below is called the Royal Arches.

We also continued to see evidence of recent mass wasting activity along the river. The rockfall seen in the picture below shows a truer color of the Redwall Limestone. It's gray on fresh surfaces, but is often stained by iron oxides leaching out of the overlying Supai Group.

Mile 43 revealed an odd sight. A thousand years ago, the Ancestral Puebloans constructed a foot bridge across ledges of Muav Limestone. From river level we could see no sign of a trail or possible route on either side of the bridge, but there it was. We joked that it was a ruse designed to catch their enemies. They would climb up there to see where it went, where they could be picked off at random.

Some of the Cambrian layers in the Grand Canyon are greenish in color, especially the Bright Angel Shale. The color comes from a mineral called glauconite. The Bright Angel is composed of what used to be ocean-floor muds, and generally forms slopes. Where freshly carved by the river, it formed the ledges seen below.

At Mile 47, we reached Saddle Canyon. I kind of awoke from my entrancement and prepared to stroll up the gentle tributary valley. I asked about the cut in talus slopes to the left of the canyon. "Oh, that's the trail" they said, "the canyon itself is far too steep to go climbing in". Oh geesh, this wasn't going to be at all that easy! We started climbing the incredibly steep talus slope, up through several hundred feet of Bright Angel and Muav layers. It...was...hot.

As always, though, the view of the river was wonderful.

The "trail" leveled briefly. It was wonderful not stepping up and over the large boulders.

The stream valley rose to meet the trail, and suddenly we were in a merry little paradise. It's amazing what a little bit of water in the desert can do. Life was everywhere.

We reached the small waterfall and the lusciously cool pool at the base. My picture doesn't have people in it, but I can assure you that every one of us submerged ourselves under the water.

At this time of year I didn't expect to find many flowers, but in the cool moist micro-climate of Saddle Canyon there were some beautiful columbines, one of my favorite flowers.

I spoke of a river within a river in the title. I was looking for something I had never seen before: the Temple Butte Formation. The Temple Butte is Devonian in age, around 400 million years, which puts the formation between the overlying Redwall and the underlying Muav Limestone. But it isn't a continuous layer. The Muav Limestone was exposed to erosion and eventually developed a series of river channels that ultimately filled with limestone as sea level rose in Devonian time. In other areas, the limestone covered the whole landscape, but after its deposition, the Temple Butte in eastern Grand Canyon was eroded again, leaving only lenses of the formation in the 400 million year old river channels. There are ancient rivers in the depths of the modern river canyon.

Walking out of Saddle Canyon, I spied a really nice example of the purplish Temple Butte between the Redwall and the Muav. If you can't quite visualize what I've been describing, I annotated the picture below. I missed the formation on my previous trips in the canyon, but once I saw it and knew what I was seeing, I began seeing it everywhere!

We continued to float down the river for four miles to our camp at Little Nankoweap Creek. The canyon was beautiful beyond words. Pete let me row again, and I even traversed two gigantic rapids. Okay, they were riffles. Okay, they weren't even that...they were piffles. But I did manage to navigate the raft into camp!

After our fourth day on the Colorado River, we pulled into camp at Little Nankoweap Creek. The camp was in a beautiful location (as nearly all of our camps were), but as I selected a campsite, my attention was captured by an oddity. There was a huge splash of reddish brown mud laid across the sandy campsite like the edge of a lava flow. What was going on?

I realized I was looking at some of the very real results of the monsoon storms of the last five days. While Page was getting pounded and nearby Antelope Canyon getting flooded (events we didn't hear about until much later), numerous tributary canyons to the Colorado River were also being flooded. We were the first to see what happened at Little Nankoweap, as there were no footprints anywhere on the new flood deposits. It was no disaster in the big picture of things, but it was a marvelous small scale example of how the Grand Canyon got grand.

Flash floods and debris flows are the tools that erosion uses to deepen tributary canyons and widen the big canyon as a whole. Rock falls and avalanches choke the bottoms of gulches, and every decade or two a cloudburst sends torrents of water down the creeks, forming a slurry mix of mud and rock capable of transporting gigantic boulders. These masses of boulders get dumped in the Colorado and end up blocking parts of the channel, forming the characteristic pools and rapids. The spring floods that once surged through the big canyon would ferry the boulders downstream or grind them into sand and silt, and in this way, the Grand Canyon took shape.

I had to take a closer look, knowing that the small mud deposit in camp was simply an overflow from the main channel. At the height of the storm, the mud was flowing over a wide area. The main channel (below) was being scoured, and rocky debris was flowing into the Colorado.

In the aftermath, a small rocky delta had formed, and the course of the river slightly changed. This particular event would soon be erased by the normal flow of the Colorado, as it was composed mostly of easily moved pebbles. I imagined the same event magnified several times, as in a once-in-a-century storm, and could see in my mind gigantic boulders changing the river on a larger scale. One of these events happened in 1966 at Crystal Rapids, turning a former riffle into the most terrifying rapid on the river (aside from Lava Falls).

We explored the channel for some distance, and found the Nankoweap Trail where it crossed the streambed. It wasn't there anymore.

The rocky steps the trail utilized to climb out of the channel had been removed by the flood (the trail is a bit left of center in the picture below).

We headed back to camp for a delicious meal of fish tacos, and hit the sack.

In the morning, I was covered with bugs. Or more properly, bug larvae. There were hundreds of them on my tarp. They were crawling all over the tamarisk tree I had camped under, and wriggling in the sand at my feet. I asked what they were, and our trip botanist pointed out that they were tamarisk beetles, and I immediately understood what was going on.

Tamarisk trees (also called salt cedar) are found all over the American southwest along river courses, but they aren't a native species. They come out of Eurasia, and having no natural enemies in their American environments, they have proliferated to the detriment of practically all competing species. They concentrate salt on their leaves which ends up in the soil, preventing the growth of other plants. They tend to form impenetrable thickets on river floodplains. They don't offer much in the way of food or shelter to most native species, and with deep taproots, they tend to transpirate vast amounts of precious groundwater into the atmosphere (some estimates put the water loss at 2 to 4.5 million acre feet per year across the southwest, enough to meet the needs of 20 million people, or to irrigate 1,000,000 acres). Some desert rivers stopped flowing on the surface after being invaded by the tree.

What's worse is that they are hard to kill. Cut them down and the taproot sprouts vigorously. Apply herbicides and many times they will sprout again anyway. A single plant might produce 500,000 seeds a year, and they can travel down the river, sprouting as they come to rest in wet sand.

I had noticed when we left Lee's Ferry that some of the tamarisks were looking a bit yellow (below), but didn't give much thought to it. It turns out that the Tamarisk Beetle loves tamarisk leaves and nothing else. After years of testing, the (also non-native) beetles were released into the wild, and they began an effective campaign of slowing the growth and spread of the tamarisk in the wild. And unlike some other such experiments, the bugs didn't start eating other native species. It is a reasonable hope that the bugs might one day lead to control (but probably never eradication) of the tree.

The trees actually provide some welcome shade in many of the river camps, but so would willows, cottonwoods, and mesquite trees if they weren't getting crowded out.

On the way back to camp, I spied an orange-breasted bird in the catsclaw acacia. I snapped a picture, and thought it might be a nice way to end a post that might seem a little depressing. But then...

...a rather majestic buck wandered through the edge of camp. So I will end with him instead.

In the next post, I get to see one of the incredible iconic sights of a Colorado River trip.

It was a busy summer. I'd like to say that I prepared extensively for my journey into the Great Unknown by getting to know the Colorado River by reading book after book, but I spent so much time organizing and conducting two other major southwest trips that when the dust settled, I only had a week to pack and read up on the river. Mostly I packed.

So it was that for the most part, the names of the rapids and the many side canyons in the Grand Canyon were new discoveries. But I knew a few of the places from reading I had done over the last forty years and I was anxious to see and photograph them. Two books that I reread this week included Down the Colorado, the Sierra Club pictorial including the words of John Wesley Powell and photos by Eliot Porter, and The Hidden Canyon, A River Journey by Edward Abbey and John Blaustein.

And that brings us to the morning in Little Nankoweap Creek. We spent the morning packing and preparing for the day, which I knew would include one of the iconic spots I had waited a long time to see: the granaries of Nankoweap.

Granaries are small cliff "dwellings" that weren't really used for dwelling. They are small buildings set high in dry cliffs where food could be stored for extended periods, safe from molds, spoilage, or pests. Maize or beans could be sealed into large pots and be kept for years (a favorite exhibit of mine at Mesa Verde National Park is just such a pot and the forty pounds of 800 year-old corn).

It's not that I've never seen granaries in the past. I've seen many dozens of them over the years. It's more the dramatic setting, perched in a steep cliff six hundred feet above a long straight stretch of the Colorado River.

Then again, 600 feet is 600 feet. Vertically, 600 feet is imposing, and there was no easy trail to the ruins. There was a very steep trail-of-use. It was probably no more than 1/2 or 2/3 of a mile long, but it climbed unmercifully in the hot sun. I was instantly regretting those many months of missed gym sessions on the stair-climber!

Still, I huffed and puffed my way up the trail, and I made it to the top. The view, if anything, was more stunning than I had ever imagined.

The granaries look much the same as they did in the Abbey/Blaustein book, published in 1977. River travelers seem to have a lot more class and sense of responsibility than many roadside tourists; I shiver to think how these would look today if there were a paved highway below instead of a wild river. I recalled a story I learned on the San Juan River in the 1980s. I was visiting a small village perched in an alcove along the river, and I remarked how wonderful the ancient dwellings looked. Our guide pointed out that a jeep trail reached the area of the ruin, and that pothunters had more than once winched the walls down looking for antiquities. They had been rebuilt three or four times. I was sorely disappointed in humanity at that moment (and many times since, for that matter).

We were exploring a wilderness, but this slope and the Nankoweap delta 600 feet below us had been home to generations of people. They grew their crops, hunted, and planned for the future by constructing these rooms in the cliff. To them, this was their whole world, aside from the stories and messages carried by the occasional traveler who wandered by.

We made our way back down to the river.

The river was revealing more of the Paleozoic history of the rocks. We had reached the Cambrian-aged Muav Limestone the previous day, and now we were seeing more and more of the underlying Bright Angel Shale. The shale is often hard to actually see, because it is so easily eroded, and tends to be covered by debris and talus that has fallen from the cliffs above. We did pass a rather striking green tower of Bright Angel Shale which had presumably been protected from erosion by harder rock above. It's called the Gray Castle.

We rode down Kwagunt Rapid (5) without problems and stopped for lunch on the beach along the eddy below. We remarked that the river seemed to be clearing after days of red mud filling the channel. The oarsmen suspected that would not be the case for long because we were approaching the confluence with the Little Colorado River.

The play of clouds and sun in the afternoon made for beautiful vistas down the canyon towards the canyon of the Little Colorado River.

A new and distinctive layer made an appearance along the riverbanks, the brownish ledges and small cliffs of Tapeats Sandstone. The Tonto Group, composed of Tapeats, Bright Angel and Muav was now complete. The rocks tell a unique story from the time of dawn of complex life on the Earth.

The Tonto Group was deposited during the Cambrian Period, the earliest part of the Paleozoic Era. The rocks range in age from 541 to 485 million years ago. It was during this period of time that a supercontinent that we now call Rodinia was splitting up into a series of smaller continents that would persist as separate entities until they rejoined into Pangea around 300 million years later. As continents split apart, a narrow sea will fill the space between them, and as they pull further apart, they will subside, due to lesser heat in the underlying crust. The oceans slowly invade the land.

The Tonto Group is the visible record of the splitting and subsidence of the Rodinian supercontinent. As the beach transgresses onto the land, the waves grind up terrestrial sediments into sand and gravel, and that is what became the Tapeats Sandstone. As the shoreline moved eastward, the offshore mud and silt eventually became the shale of the Bright Angel. Because the continents at that time were at tropical latitudes, the far offshore shoals and shallows produced the thick layers of Muav Limestone. The rocks are full of traces of the earliest complex and hard-shelled creatures to be found on the planet. These fossils include a variety of trilobites, brachiopods, archaeocyathids, and other generally unfamiliar life forms.

Trilobites were perhaps the most intriguing. They were arthropods, in the same phylum as today's insects, crustaceans, and arachnids (the term arthropod refers to "jointed-foot"). The resembled today's horseshoe crabs, or more familiar in my backyard, pill-bugs (but often much larger). A vast number of barely known soft-bodied forms were present as well. They left few fossils, but did produce many trails, tracks and burrows.

We reached the confluence of the Colorado and Little Colorado Rivers. As predicted, the Little Colorado was running red and muddy instead of the usual striking turquoise color. The water did not quickly mix, and for some distance the Colorado had a green zone and a red one.

It wasn't long before the river was living up to its name, and the muddy red color stayed with us for the remainder of the trip.

We passed one more interesting feature a short distance downstream. A white mineral was emerging out of the cliffs by the river and coating the rock. These were the salt deposits that are an important part of Hopi life. A challenging ceremony involves a long journey on foot from the Hopi mesas to the Little Colorado River where mythology and tradition states that people emerged from the third world into the fourth. Young men come downstream and collect salt, carrying it back to their villages as part of the journey into adulthood

River travelers are asked not to stop here, and we didn't. We continued down the river, pulled into camp at Carbon Creek and unloaded the boats. We had covered about twelve miles. Clouds were gathering in the sky above us...

Others may have differing opinions, but this may be my favorite picture from the entire trip.

There are, of course, many Grand Canyons. The one you will see depends on the time of day, the location of the sun and clouds, the presence or absence of storms, and your location, whether deep in the canyon, or somewhere on the rim. It also depends on the rocks you are passing through. I saw a different canyon every day, and almost every hour. It was never boring, not once. Pete, whose raft I traveled in, would probably agree that I spent every moment on the river gazing up at the canyon walls (or transfixed in horror at the lip of big rapids!).

Our fifth day ended at Carbon Creek under gathering clouds. We hadn't experienced any rain since the first day, but storms had always been lurking in the distance. We set up camp and I decided to explore a little bit. I grabbed the camera and a canteen and headed up the gorge behind the camp. The personality of the canyon had changed into one of brooding and gloom. It was partly the clouds, but it was the rocks too. We had reached the Dox Formation, part of the Grand Canyon Supergroup, the billion year old rocks that lay exposed beneath the Tapeats Sandstone.

The Dox is composed of layers of silt, shale and sandstone deposited in a variety of environments, including river floodplains, coast complexes, and deltas. In some places the formation is brightly colored, but here in Carbon Creek on this day, brown and gray seemed to predominate.

I had hoped to go far enough up the canyon to see the Great Unconformity between the Dox and the overlying Tapeats Sandstone, but I found the way to be choked with gigantic boulders that had rolled down the adjacent slopes.

Some of them displayed cavernous weathering, with deep pits and hollows that brought to mind certain horror movies...

One boulder of Tapeats Sandstone really stood out...it was 15 or 20 feet tall.

People have hiked some distance up the canyon, and have added slabs of rock to produce a makeshift stairway up the layered shale. I worked my way upward.

I would have explored farther up the canyon, but a sudden flash of light and peal of thunder told me that the storm had arrived. I had no rain gear, but I was not overly concerned since I was no more than 200-300 yards from camp. The giant boulders that impeded my progress up the canyon now provided handy shelter from the storm.

The rain came, not in torrents like the first day of our trip, but certainly enough to get wet. I gave some thought to the possibility of a flash flood, and from where I hunkered down, I made sure I had a direct line of escape onto the slopes above.

The thunder crashed and echoed through the canyons. I didn't worry; I had no place I needed to be, so I settled in and enjoyed the experience of a desert rainstorm for the next hour or so. It was even exhilarating, as I recalled the writings of John Muir when he climbed to the top of a pine tree to better observe a wild thunderstorm (I guess we're lucky he survived the experience!).

I had the sense that I wasn't alone. I looked around and realized that two of us were enjoying this storm. The lizard was enjoying it in a different way. He/she was luxuriating in the moisture, just laying there getting wet from head to toe. You can see a little droplet hanging off its tail.

Thomas Moran (1837-1926) was a painter who did much to bring about the existence of our national park system. His dreamlike images of Yellowstone and Grand Canyon popularized both regions, especially two gigantic paintings of the parks that hang in the halls of the Smithsonian. I've always enjoyed his work, even as I recognized the somewhat romanticized views of the scenes that he set on canvas. Such vistas couldn't exist in the real world, of course.

Except that they do. As the storm briefly cleared I realized I was living in a world that had previously existed only in the imagination of the long deceased painter. The clouds opened up holes that briefly let sunlight flash across the cliffs, and in other moments there was only the indirect glow of sunlight reflected off the clouds.

I took advantage of the lull in the storm and wandered back to camp.

As we ate our dinner the storm returned, and the cliffs across the canyon changed color by the moment, and appeared and disappeared as the squalls moved across our line of sight. The storms continued until the setting sun removed the energy in the air masses, and a few stars began to twinkle in the sky above us. For only the third time in the entire trip I set up my tent, but no more rain fell that night.

Looking at the picture below, the joker in me wants to say "this campsite was just plain rocky", but in reality we were simply drying off the base of the tent prior to packing it up for the day.

A stream had indeed flowed through Carbon Creek in the night, but it was no flashflood. The water did carve a small channel in the sand near the confluence with the river.

In the morning we saw the one and only scorpion of the trip. I was astounded at the small size. I've seen many of them in my travels, but never one that was barely bigger than a red ant. It was nice of the ant to wander by and provide scale for the picture. They say the smaller ones pack the biggest wallop, but according to the records no one has died in Grand Canyon from getting stung. I wasn't in any mood to experience such a thing, so we let the little guy scurry off under a rock. I shook my shoes every morning after that!

It was now day six of my journey down the Colorado River through the Grand Canyon, a trip I've been calling Into the Great Unknown, in honor of John Wesley Powell and his crew, who first navigated the river in 1869. We had floated down 65 miles from Lee's Ferry, and had now worked our way through 4,000 feet of Paleozoic sedimentary rocks that told a story of transgressing seas, tropical reefs, the growth of mountain ranges in strange places, vast sand seas, and once again a transgressing sea. It is an incredible story encompassing 300 million years, but it turns out these layers are only a small part of the whole story of Grand Canyon.

On this day we reached the hidden depths of the canyon that reveal a sequence of rocks three times as thick as the Paleozoic section. These rocks record another 550 million years of history in the time prior to the Paleozoic Era. The rocks are known collectively as the Grand Canyon Supergroup and they range in age from 1.25 billion years to 700 million years, part of the time period we call the Proterozoic Eon.

We set out from our camp at Carbon Creek and floated past exposures of the Dox Formation, which formed in river floodplains and coastal complexes. It is more than 1,000 feet thick.

Dark cliffs appeared on both sides of the river. We had reached the lava flows and intrusions of the Cardenas Lavas which were erupted just over a billion years ago on top of the Dox Formation.

How does one fit 12,000 feet of sediments and lava flows into the bottom 1,000 feet of the Grand Canyon? The rocks are tilted! In the picture below, the Tapeats Sandstone can be seen as a horizontal layer at the top of the cliff. Beneath the Tapeats are tilted layers of black Cardenas Lavas and reddish Dox Formation. The eroded surface that forms the boundary between the two sequences is called an angular unconformity. The next question might be "how did they get tilted?".

Moments later we had an answer: the rocks of the Grand Canyon Supergroup were tilted by major faults that formed when the North American continent was breaking away from Australia and Antarctica in latest Proterozoic time. We passed one of these major fault lines, the Butte Fault, near mile 66. The sedimentary layers have been dragged to a nearly vertical orientation (below).

The character of the canyon was changing once again (as I've mentioned previously, there is no single Grand Canyon; it was different every day and practically every hour). For nearly a week we had been in a deep gorge with vertical walls hundreds or thousands of feet high. Now the canyon was much wider and more open.

We saw one of the truly rare evidences of human activity from our vantage point on the river. In the picture below one can barely make out the Desert View Watchtower (just left of center on the rim). The tower is three or four stories high, and yet was barely visible among the high cliffs. The tower is one of the main tourist centers on the South Rim of Grand Canyon National Park. I thought of how many times I had stood at Desert View looking down and wondering what it would be like to float down the river. This week it was finally happening, after a wait of forty years!

We reached Tanner Rapid and pulled over to hike up to some petroglyphs on boulders that had tumbled down the slopes of the Dox Sandstone. The openness of the canyon was refreshingly different.

To many people, the canyon was not the "Great Unknown". It was their home.

I always wonder what was being said by the individuals who chipped these messages in the rock.

It was a hot day. I had the outdoor lead for the thermometer in the river and the indoor lead on the boat. 113 degrees! Yikes. We decided against a hike at lunch near Tanner for lack of shade. We went a bit farther down the river where we needed to scout Unkar Rapid.

The Unkar Delta was one of the largest settled areas along the Colorado River in Grand Canyon. The sites were occupied between 850 and 1200 AD, some 350 years! They were partly excavated in the late 1960s, and the park service has constructed a trail that visits many of the sites.

Despite the heat, I hiked the whole loop. It was hard to think of this barren area as a possible "home", but it was probable that the inhabitants moved higher up in the canyon in the hottest times of year (and conversely this would be far more comfortable a home in winter).

Meanwhile, the oarsmen were scouting Unkar Rapids (6 on a scale of 10). It looked rather ferocious, but these rafters know their craft, and the run was splashy and fun.

Ron in the other raft was pointing towards the North Rim. I looked up and saw for just a moment the arch of Angel's Window, a popular viewpoint on the Walhalla Plateau.

I've stood near Angel's Window many times, looking at the Colorado River framed in the arch (the picture below is from a trip in 2012). Look at the size of the people on the arch and consider how small they are from a river point of view! When Coronado's troops saw the Grand Canyon for the first time in 1540, they thought the river was only six feet across. They were only off by 200-300 feet! The Grand Canyon can have a huge effect on one's sense of scale.

We pulled into our camp at Upper Nevills. The river was wide and calm at the campsite, and there were nice rock ledges that made cleaning and laundry convenient. I also for the first time decided to actually test my personal flotation device and did a dunk in the river. At 52-53 degrees, the river was COLD! I commented in my journal that I was glad I hadn't been involuntarily dunked in the river yet (literary note: this sentence is an example of foreshadowing...).

Tomorrow was a big day. We were facing some of the monster rapids, including Hance (8), Sockdolager (7), and Grapevine (7). I hit the sack.

The photo above is my favorite self portrait from my journey down the Colorado River, into the Great Unknown. It's true that I appear in only a half dozen of my two thousand pictures from the trip, but this one captures best the sense of wonderment that I felt during the entire 227 mile long boating adventure. It was taken on one of the really special days of the trip, when we reached the ancients roots of a massive mountain range that today is long gone. It was also a day when I explored the roots of my own life adventure as a geologist and teacher.

And a day when I started to pay really close attention to the rapids on the river.

As a passenger on a raft (really, only a fool would allow me access to the oars in any rapid bigger than a riffle), we trust the boatmen. They are the ones who can quickly read and assess a rapid, either by standing up and observing just before entering, or by pulling ashore and scouting from above. They are the ones who make the snap decisions in the midst of chaos, deciding in an instant whether to pull left or right to get by the unexpected hole or pourover or eddy wall. They are the ones who keep their cool when the giant waves threaten to completely envelop the raft and sometimes tip it over (flipping is a highly undesirable outcome in a rapid; there's nothing fun about it at all). We trust them, and when they do their job really well, a passenger can actually become a bit complacent. If we've managed 40 or 50 rapids without problems, well, it can't really be that hard can it? And that's when things can get dicey.

Passengers play an important role in the run of a rapid, so we have to be paying attention as well. It's hard to imagine that pulling the oars makes any difference in the chaos of a rapid, but it does make a big one. Inches sometimes count. And when the raft threatens to flip over, the passengers have to be thinking fast enough to "highside", to fling themselves towards the rising side of the boat during a tip-over, using their weight to hopefully push the boat back towards the horizontal.

Why was I suddenly watching rapids with a renewed interest? We had reached the point on the river where John Wesley Powell was inspired to write one of his most famous passages, the one which also inspired the name of this blog series:

We are now ready to start on our way down the Great Unknown...We are three quarters of a mile in the depths of the earth...We have an unknown distance yet to run, an unknown river yet to explore. What falls there are, we know not; what rocks beset the channel, we know not; what walls rise over the river, we know not.

The next morning he adds:

At daybreak we walk down the bank of the river, on a little sandy beach, to take a view of a new feature in the canyon. Heretofore, hard rocks have given us bad river; soft rocks, smooth water; and a series of rocks harder than any we have experienced sets in. The river enters the granite!

We can see but a little way into the granite gorge, but it looks threatening.

He and the mountain men who served as his crew had already been on the the river system for two months, and with their inadequate clumsy boats had run or portaged many dozens of rapids that were terrifying. They were running very low on food (the diet: unleavened flour, dried apples and rancid bacon). And now the nature of the rocks exposed along the river promised rapids far worse than any they had encountered upstream.

Why were the rapids worse?

Indirectly, it was indeed the harder rocks. They were entering a part of the canyon composed of harder rocks than anywhere else along the river. It isn't the rocks themselves that make bad rapids, though. The river does not fall over ledges and waterfalls. Rapids on the Colorado River happen because of debris flows that enter the channel from the small tributary canyons. The debris in essence dams the river and forces the river channel to the side, making the cross-sectional area of the channel much smaller. Since the same amount of water in a river passes a given point in a given amount of time (cubic feet per second is one measure), the river must speed up to pass the barrier. You can see this effect in the picture above in Nevill's Rapid.

The severity of a rapid is determined by the volume and size of the boulders in the debris flows, and canyons cut into harder rocks produce larger boulders. Sprinkling a few giant boulders throughout a rapid turns a riffle into a terrifying roller coaster ride.

So that was the day we were facing. We would be entering the Granite Gorge of the Grand Canyon for the first time, and we would now need to run a gauntlet of the biggest rapids to be found on the entire river. It started with Hance (8 on a scale of 10), Sockdolager (7), and Grapevine (7). The next day would include Horn Creek (9). The day after that, Granite (8), Hermit (8), and the ultimate rapid, Crystal (10). These would be followed the same day by the seven rapids of the gemstones (Agate, Sapphire, Turquoise, Emerald, Ruby and Serpentine, ranging from 5 to 7). And 70 miles downstream (with plenty more rapids in-between) Lava Falls (10) awaited our arrival.

We came around a bend in the river, and I encountered a familiar sight in the midst of the Great Unknown. I had been here before! Not on a river rafting expedition, but on a backpacking trip in 1976. It had been one of the most important events in my young life, because it was the trip that set me on the road to becoming a geologist and teacher.

Geology of the Grand Canyon was actually one of the more difficult courses I had ever taken because not only did we need to master a lot of geology in a short time, but we also had to prepare for a challenging backpack down and then back up a series of officially unmaintained trails in the canyon (the New Hance and Grandview trails). The co-requisite for the class was a 2 unit physical education course in backcountry camping that including an entirely separate shakedown trip in the mountains of Southern California. When I came out of the Grand Canyon six days later I knew what I wanted to do with my life.

Of course, a few things have changed since 1976. Geotripper weighs, um, a lot more than that gawky teenager on the right in the picture below. Picture quality has improved, not so much because of better photographers, but it used to be expensive to take and develop pictures, so we never took very many. Plus we were using the old Kodak Instamatic cameras or something similar.

Still, seeing these pictures a few years ago on Facebook (thanks to J. Elson) brought a shock of memories, and now for the first time in forty years I was once again standing at the rapid that made a geologist out of me.

Only this time my mind was on other things. Back then when we finished, we turned around and started hiking back out of the canyon.

We were about to run a major Grand Canyon rapid in boats that suddenly seemed really small. Just like these river rafters in 1976. I noticed that the two biggest boulders haven't moved, and that the rapid was as chaotic looking as ever.

We had reached the base of the Grand Canyon Supergroup, and could now see the three formations that make up the oldest units: the Shinumo Quartzite, the bright red Hakatai Shale, and the basal Bass Limestone (intruded by basaltic dikes). The rocks are tilted about 15 degrees, giving the illusion that the river gradient is even steeper than it already seems. It can't have been a comforting sight to Powell and his men in 1869.

The Grand Canyon Supergroup sits on a mountain range of Andean proportions. Or more properly stated, the layers were deposited on the low erosional plain left behind when a mountain range of Andean proportions was completely washed away. The black schists and reddish granite intrusions once lay some five miles deep in the crust, and now they have been laid bare by the cutting of the Grand Canyon.

The rocks today are called the Granite Gorge Metamorphic Suite, and they formed in a series of collisions between a group of volcanic islands (called terranes), and the ancient North American continent around 1.7 billion years ago. The metamorphic schist and gness units were intruded by granitic magmas at intervals between 1.7 and 1.4 billion years ago. And now those rocks are exposed in the very deepest part of the Grand Canyon.

We successfully negotiated Hance Rapid (not without getting positively soaked), and looking back upstream, I could see the basalt dike that I had found so utterly fascinating on my first trip into the canyon.

The canyon was dark, but I did not feel as sense of brooding. I was exhilarated, my imagination seeing the peaks and canyons that must have existed here in the distant past, mountain slopes which would have been utterly lifeless and barren. Deep gorges must have been cut by rushing rivers that were never seen by any living thing. Entire Grand Canyons could have been carved here and we will never know of their existence. We now entered a fascinating world of exceedingly rugged vertical canyon walls. The silt and sand polished the hard granite and metamorphic rock.

Sockdolager Rapid (the word is an archaic term for knockout blow in boxing) was a fun ride, nothing like the terror-filled lining and portage in Powell's writings.

It was hard to find a spot to scout, so the boatmen checked out the rapid by standing up as they approached.

Between rapids the river was calm, and the canyon walls rose straight from the water.

The metamorphic suite was composed of the most diverse and beautiful rocks that I had seen anywhere on the trip. The polishing simply added to the beautiful sculpted appearance of the rock.

We arrived at camp in Cremation Canyon by 2:30. We had pulled in early because we would be saying goodbye to three of our fellow travelers who would be hiking out of the canyon from Phantom Ranch, and meeting three others who would take their place for the remainder of our journey.

I turned in early once again...tomorrow we faced the biggest rapids so far on the trip.

We were really out of touch. In the eight days we had been gone on the Colorado River (the Great Unknown), I sent one text from camp the first night (surprise, cellular coverage at mile 6!), and on the second or third night I had a two-minute conversation on the emergency satellite phone (we couldn't download a waiting message on the phone so we each checked on our loved ones; it turned out to be a "Welcome to Verizon" message or whatever satellite company it was). I had seen not a single sign of any sort since we left Lee's Ferry aside from some number markers on the Unkar Ruins trail. So the beginning of our day was a real culture shock. Less than a quarter mile from our camp at Cremation, a bridge came into view!

And what a bridge! For something like 400 miles, from Lee's Ferry to Pat Tilman Bridge and Hoover Dam not a single bridge crosses the Colorado River. How many rivers in the world in this day and age have that kind of a record? In any case, it was not a bridge for cars, but for hikers and mule trains. We had reached Grand Central Station of the Grand Canyon: Phantom Ranch.

Just how urbanized is Phantom Ranch? It has signs for one, like this one that greets boaters fresh off the river. And there are water spigots with treated water just 100 yards from the boat beach (our fresh water stores were becoming slim). And there were two dozen or more things called permanent "buildings", which apparently are used by other human beings for cooking, sleeping, showering, and even eliminating human waste! With flushing water! One of the most amazing contraptions I saw was a "pay telephone", an instrument I was able to use to contact the outside world for news. I was relieved to find that there had been no zombie apocalypse, and that life was more or less normal beyond the rim of the canyon.

And...there is green stuff all over the place, in spite of the 100+ degree temperatures that last all through the summer season. Cottonwood trees and grass and stuff. It turns out that Phantom Ranch was located along Bright Angel Creek, one of the larger tributary streams flowing into the Grand Canyon. Bright Angel Creek begins in earnest at Roaring Springs around 10 miles upstream. The water bursts out of the rock at the base of the Muav Limestone as an instant river. There is so much water that pumping stations were built so that the springs supply the water needs of the developments at both the North Rim and South Rim of Grand Canyon National Park: all the hotels, the campgrounds, the visitor centers, and the restrooms. And there is enough left over that the creek flows all year at the Ranch and supports a robust population of fish (eight native species originally and two introduced trout species that are being removed).

After talking on the phone, mailing postcards, and consuming both the most expensive and most refreshing iced lemonade I've ever had, we got back on the rafts and began the second half of our journey. A short distance downstream, just below the second footbridge, we met the new members of our party, and had lunch (salmon salad pitas).

We were deep within the Granite Gorge and not a whole lot of granite was to be seen. The cliffs were mostly composed of dark schist or gneiss. There were thin dikes and stringers of red and pink granite and pegmatite here and there. But still, looking at the sheer walls coming straight down to the water, I could understand the apprehension of John Wesley Powell and his men as they ventured through this canyon in 1869. They were getting used to rapids by this point, but they had almost always been able to portage the boats around the worst rapids, or let them down the raging river by rope. Both of these methods were difficult at best, but with the sheer walls they were forced to run some rapids that they would have rather avoided.

We were approaching our first class 9 rapid at Horn Creek. As we went in, I experienced one of the really big holes with a huge standing wave. We kind of shot right through it, meaning I was thoroughly and completely drenched.

It took awhile to dry off enough that I felt I could retrieve my camera from the dry bag, so my picture looking back at Horn Creek Rapid makes it look a great deal smaller than it actually is (below).

Perhaps the comic I drew that night can provide some perspective...

We moved on downstream. It was a short day on the river, only five miles total, so we drifted with the current for awhile, passing gigantic towers of schist and granite. The peak in the picture below reminded me of Sentinel Rock in Yosemite Valley.

We passed an intriguing little island just before camp, with a tamarisk tree surviving somehow on a solid mass of schist and granite. This rock and the tree must surely be inundated during high water, and soil must be washed away on a continual basis. Then again, as of 1963 the flows of the river have been tightly controlled, with only a few floods (planned and unplanned) since then.

With the leisurely day, I had a chance to take some close up shots of the metamorphic rocks.

The forms are fascinating. As we noted in yesterday's post, these rocks are the deep crust remnants of a 1.7 billion year old mountain range that once extended from at least California (Death Valley area) to Mexico and perhaps Oklahoma and Arkansas. The mountains were pushed up as a result of the collisions between a series of island terranes and the core of the North American continent.

These rocks used to be mud and silt on the ocean floor, or volcanic rock like one sees in Japan or the Aleutian Islands. The rocks were crushed, buried, and heated nearly to the melting point, but not quite (different minerals melt at different temperatures, so part of the rock could have been molten, but not all of it). The rocks were twisted and folded like saltwater taffy, and later on they were intruded by hot masses of granitic magma, forming the pink rock in these pictures.

The granite has huge crystals of potassium feldspar (the pink/orange mineral), clear quartz, and plates or sheets of shiny muscovite mica. Such rocks are called pegmatites. Other beautiful minerals can sometimes be seen, including black biotite mica, and reddish brown garnet.

I was walking in a small unnamed canyon just upstream of Salt Creek (our camp was very creatively called "Above Salt Creek"). There was a small trickle of water.

The little bit of erosion has attacked the boundary between the schist and the granite, highlighting a fold in the schist.

My ankles were bothering me again, so there was no way I was going try to climb the jumble of boulders at the head of the canyon, but before I got there my attention was drawn to one of the strangest rocks I had seen in awhile. It was bright red.

Most of the time, geologists are pretty loose with their definition of the color red, using it to describe a lot of brown and reddish brown rocks and sediments. But this stuff was really red. It was essentially fine-grained, but may have had small phenocrysts (small crystals) of a white mineral, maybe feldspar. I couldn't tell, and to my shame I was caught in the wild without my handlens! It was fairly easy to weather, as you can see from the mineral veins that stand out in relief (this is material, probably calcium carbonate, that filled cracks and fissures in the rock much later).

I'm guessing it might have been some kind of metavolcanic rock, but really as a non-petrologist, I am not at all sure. Any ideas out there, gang?

The shadows grew longer in the dark canyon as the boatmen checked their rigs. Tomorrow was promising to be the most challenging day of the trip, with at least ten major rapids, including Granite (8), Hermit (8), and Crystal (9-10).

We were treated to a wonderful sunset. Once again I hit the sack early, just moments after sunset.

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