Into the Great Unknown: Vulcan the Fire God says "You Call That Little Piece of Concrete a Dam?"

Dam engineers sure love their dam creations. The Colorado River, being the only river of note draining the Colorado Plateau, was a target of their fevered dreams, and major projects have "tamed" the river, most notably at Hoover Dam/Lake Mead, and Glen Canyon Dam/Lake Powell (above). Those who administer the giant concrete plugs love to cite the statistics: Hoover holds back 28 million acre feet, Powell 24 million, Mead is 112 miles long when full, Powell is 186 miles. It can't be denied that the concrete monsters have had a huge effect on the ecosystems of the river. Glen Canyon is entirely submerged. The river downstream runs cold all year, and surges high and low in response to electrical production needs. Native fish and flora struggle to survive in the new regime.

We were at the end of our thirteenth and starting the fourteenth day of our journey into the Great Unknown, a rafting trip down the Colorado River from Lees Ferry to Diamond Creek. I had taken an involuntary swim through Lava Falls Rapid that afternoon, but with the swim having been a far less terrifying experience than the first flip back at Crystal, I was feeling okay. Passing through Lava Falls represents to many the climax of the trip, and the last two or three days are sort of a winding down of the journey, with few large rapids.

For me though, the last two days were some of the most astounding because we had reached the site of one of the most extraordinary geological stories in the entire history of the Grand Canyon. Visitors to the main tourist areas on the north and south rims of the canyon never see the rocks that lined the canyon walls around us, and are often surprised to find they exist at all: miles and miles of basaltic lava flows!

The edge of the Colorado Plateau is punctuated by a series of north trending extensional ("normal") fault zones. They represent the boundary zone between the thick crust of the Colorado Plateau, and the thin extended crust of the Basin and Range Province that reaches across Arizona, Nevada and eastern California. When the crust stretches and breaks, pressure is released in the Earth's mantle below, allowing partial melting of the hot pliable rock. The resulting magma follows the fault zones to the surface. Between 1.8 million and just 1,300 years ago, at least 150 eruptions took place in the vicinity of the western Grand Canyon, covering 600 square miles, forming the Uinkaret Volcanic Field.

Most importantly, at least 13 of these flows spilled over the edge of the canyon and filled the canyon bottom. Vulcan, the fire god, had built his own version of Bureau of Reclamation dams. They weren't small dams. They were hundreds of feet high, and one topped out at least 2,500 feet (Glen Canyon Dam is 710 feet tall). It was the remnants of these lava flows and lava dams that surrounded us as we floated down the river. It was the first time I had seen these rocks. I was mesmerized (yes, we geologists are a strange lot).

What's even more incredible are the lakes that formed behind the dam. The largest dam formed a lake that backed the river up into Utah. If it happened today, the lava dam lake would inundate Lake Powell. It would make for a long hard rafting journey, but the rapid at the end would have been memorable...

Even more mysterious would be how the lakes met their end. It's still the subject of some research, but evidence suggests that at least five of the lava dams failed catastrophically, collapsing and ending the lake in days rather than years. What kind of evidence? The most compelling would be river deposits containing basalt boulders 115 feet across. How do you move boulders that big?

The amount of water unleashed on the lower canyon by such a failure is almost unimaginable. A modest 'fake' flood produced by releasing water from Glen Canyon Dam up the river might involve flows of 40-45,000 cubic feet per second. The largest historically recorded flood (in 1884) produced flows of about 300,000 cfs. A researcher has found evidence of a flood of 400,000 cfs around 4,000 years ago. Estimates of major floods during the Pleistocene ice ages range in the vicinity of a million cubic feet per second.

The collapse of a 1,500 foot tall lava dam may have produced a flood of 15 million cubic feet per second. That's more than 30 times larger than the biggest flood ever recorded on the Mississippi River. That's how you move 115 foot boulders.

Pictures of gigantic floods filled my imagination as we drifted past lava flow after lava flow. At first, the most vivid outcrops were the flows that had spilled over the rim in the vicinity of Lava Falls and Whitmore Wash. As we floated downstream, the basalt flows tracked along the river, forming low cliffs that went on for miles. The longest flows traveled more than sixty miles down the river bed.

In places the lava flows were thick enough to develop columnar jointing, similar to places like Devils Postpile in California or the Giant's Causeway in Ireland. The columns form when the lava flow pools and then contracts while it cools. The contraction causes the vertical fractures to develop, and they characteristically form hexagonal columns or sometimes rosettes. All in all, the day had been fascinating.

Lava wasn't the only feature of the day. At Whitmore Wash we had a chance to hike up to some interesting pictographs on a sandstone panel a few hundred feet above the river.

 The view up the river was fantastic...

We camped at the very creatively named 202 Mile Camp. While I was cooking, my nephew came up to report that the bank of the river was collapsing. I wandered down to have a look and found that an underwater slide was causing large slabs of sand to be pulled towards the river, forming a large arcuate landslide scarp. After seeing a gigantic normal fault to begin the day, it was interesting to see a small-scale version of the same kind of faulting along the riverbank. The little collapsed block in the center would be called a graben.

The slide ultimately ate up a lot of the shoreline, more than 30 feet, and it was clear that a lot of sand was being lost to the deeper part of the river channel. Ever since the floodgates of Glen Canyon Dam closed in 1963, sand has been disappearing along all the shorelines of the river. There have been a few attempts to produce artificial floods that have temporarily moved sand back onto the beaches, but without the sand that is now trapped in Lake Powell, the beaches are going to continue to disappear.

At the end of the day, the moon made an appearance. It was the first we had seen of it on pretty much the entire trip. I had enjoyed seeing the Milky Way each night, and the moon would have obscured many of the stars, but it was nice to see the beautiful crescent setting over the basalt cliffs.

With the last of the twilight, I hit the sack, realizing we were down to our final two days on the river. Our takeout at Diamond Creek was only 24 miles downstream.

Into the Great Unknown: Zero Hour at Lava Falls Rapid

I was going to title this post about our trip into the Great Unknown "Courage, Redemption, and the Triumph of the Human Spirit at Lava Falls: Geotripper Rides the Big Rapid", but I knew my fellow travelers would all yell "Bullschist" in four-part harmony like the townspeople in Blazing Saddles. So we'll settle with what I put up up above for a title.

Still, the oarsmen have a saying: "You don't f*ck around with four rapids in the Grand Canyon, Hance, Horn (or Granite? I don't always listen well), Crystal, and Lava Falls". And they were right. I took a long and harrowing swim in Crystal Rapid several days earlier, and I wasn't anxious to do such a thing again. For several days now, the oarsmen in our group had been talking about Lava Falls, and now having passed the massive volcanic plug of Vulcan's Anvil, we were at the top of the worst rapid on the Colorado River, and one of the toughest rapids in North America. It is rated at Class 10 out of 10 on the river runners scale.

Really, how many rapids rate a 90 page geological analysis? You can see it right here: http://pubs.usgs.gov/pp/1591/report.pdf .

A quote from the ever-staid and formal geological investigators:

Lava Falls, at river mile 179.4 on the Colorado River in Grand Canyon, is one of the most
difficult navigable rapids in the continental United States and is the standard against which all rapids in Grand Canyon National Park are judged for navigability.

I had been thinking about Lava Falls a lot over the last couple of days, and after my dunking in Crystal Rapid, I was pretty sure I would elect to walk around the rapid. Looking at my journal, I see that I even said so twice in the days leading up to our arrival. Still, I told myself that I would take a look and consider it.

Two very strange things happened to me when I climbed up to the scouting ledge at the top of the rapid. First, I didn't panic. It made a difference actually seeing the rapid, in contrast to thinking and pondering on the idea of a monster rapid. Somehow the analytical part of my mind was looking at the rapid and picking out the possible route through the pinball arrangement of holes, rocks and ledges, and it managed to suppress the urge of the other part of my brain to run down the talus slope and await the arrival of the broken boats and injured bodies of my comrades at the base of the rapids. I even managed to see the route we needed to follow through the rapid (confirmed a moment later as I listened in on the discussion taking place between the oarsmen).  Where would you go, looking at the picture above? Take a guess, and then look at the photo below...

The second very strange thing that happened was that I experienced a Hitchcockian case of vertigo every time I looked at the rapid. The whole scene swam in front of me whenever I looked at the waves. I've never had vertigo in my life, and didn't even know what to call it at the time, but I would look away to the cliffs above, and no problem. I'd look at the river again, and it would start wavering and swimming in front of me. As best as I can figure, the reptilian core of my brain was desperately trying to overcome the analytical part of my brain and toss it into the river so I would do the safe thing and walk around the rapid.

Why is Lava Falls such a treacherous rapid?

All the rapids on the Colorado River in the Grand Canyon exist because of debris flows. These floods of giant boulders and mud emerge from the tributary canyons and pile into the river, pushing the flow into a narrow channel on one side or the other. The river has to speed up as it passes through the constriction, and it drops anywhere from a few feet to as many as 30. The severity of the rapid is determined by the length of the rapid, the drop, and the arrangement of large boulders along the way. The level of the Colorado River is also an important consideration. Some rapids are better if the flow is higher. Others are better at low flows.

Lava Falls formed because of debris flows that emerged from nearby Prospect Canyon. During intense cloudbursts, water pours down the cliffs of the Supai Group and overlying Permian formations, and drops over a 1,000 foot cliff of Redwall Limestone. The waterfall hits the slope debris at the base of the cliff, and forms the debris flow via what the researchers call the "firehose effect". The deposits along the river record a great many flooding events over the last 3,000 years. One of the prehistoric events dammed the river to a depth of nearly 100 feet. The rapid formed by that event would have dwarfed the present-day Lava Falls. More recent debris flows altered the rapid in 1939, 1954, 1955, 1963, 1966, and 1995. The 1939 event was the largest historical debris flow in the modern history of the Grand Canyon, larger even than the 1966 event that turned Crystal Rapid into such a monster. The flow was estimated at 35,000 cubic feet per second. That would be considered a high flow on the main Colorado River. The pile of debris constricted the river to only 20% of its normal width for a time (about 50% today). Lava Falls had become a monster rapid.

Lava Falls Rapid has a gigantic ledge at the top that forms a huge standing wave that can trap a small raft for hours. Routes can be possible on both the right side and left, but the left side has large boulders that can trap boats near the base of the rapids. High flows can diminish the danger. Most runs occur on the right, but there is another huge hole and standing wave that must be avoided on the far right side. Boats have to punch through the huge V wave, avoid the huge boulder called the Cheese Grater, and then navigate past two other gigantic waves, the Kahunas. It's the worst rapid, but short. The whole ride lasts less than 20 seconds if done right. Done wrong, and you'll be pitched into the water for a wild ride, or caught on a boulder for hours (see an interesting story about one such trapped boat right here).

Let's see what a good run through Lava Falls looks like. Ron was one of the most unflappable oarsmen I've ever seen, and here he can be seen taking Lisa and my nephew Samuel through Lava Falls. He catches the right side of the ledge above...

They punch through the V wave...

They nearly get swamped by the gigantic Kahuna Waves while simultaneously avoiding the Cheese Grater on the right...

And they make it through, wet but unscathed!

My brother Mark and his wife Carol are guided through by their oarsman Gerrish, and even though their boat was oriented almost 90 degrees, they made it through too. 

Mark took a GoPro cam so you can watch the ride from his point of view right here:

Meanwhile, I was still up on the scout rock watching my brother's family running the rapids. The moment of truth had come and someone behind me asked if I was going to ride the rapid. A disembodied voice quite separate from my conscious mind said "yes". I wasn't sure who spoke, but since everyone was looking at me, I guess it had been me. I don't know what I was thinking... I pulled Pete, on whose boat I was riding, off to the side and said to him "I need an honest answer...is it better if I'm in the boat (extra weight, lots of it), or not?" He said he needed the weight to help punch through the waves, so I was going.

We got in the boat, and this time the camera and the journal were stowed as tightly and securely as possible. I wasn't going to lose a second camera, and the loss of my journal would have been devastating. I hunkered down in the front of the raft and we pushed off.

A story of redemption and courage would end with a victorious run through the rapid, and a confirmation that it is always better to bravely face your fears. Always get back on the horse after you are thrown. Jump back into the battle after your nose has been bloodied. The story ends with an affirmation of the human spirit, and a slow motion montage of arms thrown in the air in victory. That's how the movie script would end. Here's what actually happened, courtesy of Bruce Burger who was shooting our ride from the scouting rock (his effort to get the movie posted is greatly appreciated!):

Yup, we flipped on the V wave. Personally I don't think anything was wrong with our approach. Our boat was just too short and too lightly loaded, and we simply caught the edge of an unlucky wave. In any case, I was in the water again. It was a shock, but it was far less terrifying this time around. I bobbed up quickly and the boat was right there. I grabbed on, and once again I realized I was in front and headed towards being crushed against the Cheese Grater. I quickly shifted to the side of the boat, but the current shifted left, so we missed the big rock. We rode out the two Kahuna Waves and the river quickly settled down. I was in calm water within a minute or less.

I found out that Pete had a worse time of it, because he got trapped under the boat briefly, and tumbled head over heels in the dark water. That had to be a horrific ten seconds (and seriously, they would have been the longest ten seconds of anyone's life), but by the time I was able to check behind me he was swimming too.

Once again, Barry and Bev came to the rescue, and since I had only been in the water for two minutes or so (and being a hundred miles downstream the water was not quite as cold as before), I was able to help climb onto their boat, and I was even able to be an active participant in catching our overturned raft. We got the boat flipped back, and the only losses were my rowing gloves and my hat (I had a spare). The camera was safe, and a few moments later I snapped a self-portrait of the not quite drowned river rat.

And that was that. We had survived the greatest rapid on the river. It's hard to say if I should have walked. I feel good about facing the challenge and being part of the team, but I also just a bit more nervous every time a medium to large rapid loomed. But for the rest of the trip there were only a few, and I ended up with a neat story to tell.

We headed down the canyon to our camp at Middle Chevron. It was situated beneath an immense cliff of basaltic lava that would be a dominant feature of the canyon for much of the remainder of our journey. We had a delightful meal of chili and cornbread with cheesecake for dessert. I laid down to sleep and watched lightning flicker in the eastern skies. The stars blazed overhead, and soon I was asleep. The trip was now "post-lava-falls". I slept soundly.

Into the Great Unknown: "Disaster" in National Canyon and the Volcanoes of Grand Canyon

Yeah, I was not feeling all that comfortable. It was day 13 on our journey into the Great Unknown, the Colorado River through the Grand Canyon. Day 13, and Lava Falls Rapid, the worst rated rapid on the river was...13 miles downstream. And I didn't know it yet, but we would arrive there at 13:00 hours. I'm not at all superstitious, but it was nice when the message written in the sands of time on the river shore appeared. Okay, I put it there myself, but I was apprehensive just the same!

We were camped at the mouth of National Canyon, which for many years was one of the larger and more popular campsites on the river. And then in the summer of 2012 it was hit by an apocalyptic flash flood that just about wiped the camp out of existence.

It's hard to imagine the scale of the flood. Estimates put the flow at 15,000 cubic feet per second. To put that into perspective, the flow of the entire Colorado River for most of our journey was around 8,000 to 12,000 cfs. And the flood was witnessed. A Western Rivers Expedition boat was passing by, and captured the flood entering the Colorado. Check out the video below by Joe Clark, one of the river guides:

Our campsite was rocky, but we found places to sleep. The rocky plain was barren of plant life. There is hope that a few artificial floods may ultimately deposit more sand on top of the bouldery deposits, but I wonder if the Bureau of Reclamation will be doing any artificial floods in light of the ongoing drought.

In any case, the experienced members of our crew were curious about how much the canyon above the river had been changed by the flooding. To me, the canyon was a beautiful place, regardless of how it might have once looked. How could I know any difference?

I could see that eroded ledges of Muav Limestone had indeed been buried in debris, and barely a single plant was visible along the course of the creek, despite the presence of a clear babbling stream. The going was tough in a few places. Boulders choked the channel.

The barren nature of the canyon was almost disturbing. It felt like there should be plants growing along the water. It drove home the point that no matter what ever else may happen, the rocks remain. Battered, broken, or polished smooth, they will last as everything else passes. But the rocks were also very beautiful, though, and the narrows spectacular. It occurred to me that this canyon, were it to be anywhere else in the country would be a national park or monument in its own right. Here, it was simply a tributary to the larger river, one of many.

The sun was high, and it was getting hot. We got onto the river and rowed downstream. We had reached a fairly long stretch with no major rapids, and lots of quiet passages through vertical canyon walls of Paleozoic sediments. In places we could see all the way to the canyon rim four or five thousand feet above us. The rim, and the world beyond, seemed remote and very far away.

I did a double take at Mile 176. Thousands of years ago massive landslide had broken away from the Supai cliffs out of sight above, and had come thundering over the Redwall Limestone, coming to rest near the river. It is called the Red Slide.

Over time erosion began to tear away at the debris-covered slopes, but here and there a large boulder protected the underlying soft material. The boulders were left standing on spires called hoodoos. It was yet another strange sight along the river.

I was on the lookout, because for the first time we would be seeing a new rock unit (the last "new" rock unit had been 100 miles upstream). It is not a familiar rock to the vast majority of visitors to the Grand Canyon, and in fact, most people are surprised to find out that such rocks are present in the national park: there are volcanoes and lava flows!

I looked high on the walls, and there was the first one, a fragment of black basalt clinging to the cliff. It was an exciting moment for me, because I've never seen these rocks before. I will deal with the profound effects of the lava flows in one of the next posts.

There were more signs of volcanism along the river where a sill had intruded into the Muav Limestone. It was one of the finer examples I've ever been able to photograph.
Soon we could see the source of some of the lava flows, a cinder cone on the high canyon rim called Vulcan's Throne.

We could also see the long tongue of lava from Vulcan's Throne that had reached the river. John Wesley Powell's description remains one of his most poetic writings:

Just over the fall a cinder cone, or extinct volcano, stands on the very brink of the canyon. What a conflict of water and fire there must have been here! Just imagine a river of molten rock running down into a river of melted snow. What seething and boiling of the waters; what clouds of steam rolled into the heavens!

And then, one of the strangest sights of all. A huge mass of congealed lava stuck right in the middle of the river. It was a plug of lava that filled the vent of one of the cinder cones. Called Vulcan's Anvil, it seemed like a message or a warning to river travelers, which indeed it is.

When we passed the anvil, we know we had less than a mile to one of the biggest challenges on the river: Lava Falls Rapid. The moment of truth had arrived...

The Anvil receded into the distance, and we prepared to scout the wildest rapid on a wild river.