Monday, July 22, 2013

Great Flashflood Video from David Rankin

It's that time of the year in the American Southwest - the annual summer monsoon. Just the other night Helen and I drove back from the South Rim of the Grand Canyon and witnessed a stupendous storm cell that moved southwest over the San Francisco Peaks and down to the western Mogollon Rim. The lightning was ,well... electric... and sheets of rain fell on us for a full 20 miles from Kendrick Park to the city of Flagstaff. Our windshield wipers could not keep up with the spend that the rain fell. We heard from friends at Phantom Ranch in the canyon that Bright Angel Creek flashed on the night of July 20. It is a great time to be on the Colorado Plateau!

David Rankin

My friend and colleague in Page, AZ, David Rankin has been chasing flash floods with his video camera for years and seems to have perfected the art of predicting what drainages will flash, when they will arrive at a certain place, and then putting himself in position to film them. I have been enjoying his work for years but these new clips from an event that occurred on Wahweap Creek on July 18 of this year are especially informative and entertaining.

WARNING: Do not attempt these stunts at home! David has been watching flash floods for years and knows the inherent dangers and places himself in a position where he can escape if need be. Notice that none of these shots are in closed or confined canyons. They are all in open ground where there is an avenue of escape.

You can view the clips here. This is flash flood video like you've never seen it before! Note how slow the head of the flood seems to be moving. This is because of the "wall" of debris that acts to slow the front end down. Note that the ground where the flood arrives is not wet - it did not rain in this location at all. These are powerful events and we are lucky to see them this way. Thanks Dave!

Thursday, July 18, 2013

US Highway 89 Landslide - Solution Identified

Image courtesy of ADOT and taken from their Highway 89 web banner
Nearly five months after it occurred, the Arizona Department of Transportation (ADOT) has released the results of its long awaited geotechnical report on the cliff rupture. Readers will recall my previous postings on this blog about this major geologic and social event in northern Arizona.

I first reported on the event when I received an e-mail from a friend while traveling in Luxor, Egypt just a few hours after it happened. You can read that here. Reporting on this event from Egypt was one of the strangest blogging experiences I have ever had, not only because I had such limited time to write a blog but also because I was hearing up-to-the-minute news about an event happening at home while on the other side of the globe. I wrote a second piece about the event here, where I speculated that the slump might have occurred on road fill material only. That speculation was put to rest in a third posting here and my last posting went up here that described in more details what ADOT was up to with the testing.

Now the results of the study can be read here. A copy of the full 436-page study can be downloaded from that page. A summary is that five alternatives were considered but the chosen alternative is to cut back into the cliff an additional 60 feet and then use that material to form a rock buttress at the foot of the slide, some 135 feet below the current right-of-way. There are good graphic that visually describe the fix. The cost will be $40 million and it will take approximately two years to complete. $35 million has already been authorized for the pavement of Navajo Route 20 just o the south and east.

Kudos to ADOT for choosing what is likely the best all-around alternative for the affected communities.

Tuesday, July 09, 2013

Colorado River Geologists Win Award For Basin Spillover Research

ADDENDUM: on August 26, 2013 I added an interview published in Arizona Highways with head researcher Kyle House. You can access that interview here. It is quite good and gives a nice rendition of their work.

A trio of geologists who worked out the evolutionary history of the Lower Colorado River (from Hoover Dam to the Gulf of California) have won the prestigious Kirk Bryan Award from the Geological Society of America. An article appearing in a St. George journal can be read here.

Kyle House, Phillip Pearthree, and Michael Perkins published an article in 2007 that detailed their findings while working along the lower river corridor. They described a sequence of deposits in four basins that each contained (from bottom to top) A) Closed basin material only; B) coarse cobbles from bedrock sills located on the upstream margin of each basin; C) freshwater lake deposits; and D) capped with unequivocal Colorado River gravels and sand. Their conclusion was that once formerly disconnected basins were sequentially filled and spilled to integrate the lower river. A marvelous piece of geologic detective work!

Photo courtesy of Kyle House
Deposits exposed near Laughlin, Nevada along the lower Colorado River (below). The lower half of the outcrop contains rocks deposited exclusively in a closed basin before the lower Colorado River was formed; the gray cobble deposit midway in the outcrop represents debris from a bedrock sill that was overtopped and destroyed when an upstream lake basin "filled and spilled"; and the thin whitish cap on top is a remnant of the Bouse Formation, freshwater lake deposits laid down when this basin filled with water. Once this basin filled, it spilled to the next one farther south (left).

You can read this story in the new edition of my book, "Carving Grand Canyon". Here is an excerpt from pages 134 to 137:

Evidence for a Young Colorado River

Knowing that some geologists favor ideas for an old ancestor to the Colorado River, it might seem exceedingly incongruous for others to present evidence for a quite young river. Yet startling results in this area were forwarded at the 2010 workshop. Working in the area along the lower river near Laughlin, Nevada, and Bullhead City, Arizona (and not coincidentally where Blackwelder first suggested evidence of a young river), Kyle House, Philip Pearthree, and others showed convincingly that closed, disconnected basins became sequentially filled with water, overtopped their bedrock divides, and created a course for the lower Colorado River. Their results show that this fill-and-spill episode spans a 1.5-million-year period that began after 5.6 million years ago and finished by 4.1 million years ago. These studies also helped to clarify the problematic origin of the Bouse Formation.

Photo courtesy of Jon Spencer

Picture of the Bouse Formation near Cibola, Arizona. The Bouse contains evidence for freshwater lakes along the course of the lower Colorado River. These lakes were rapidly filled (geologically) and then spilled to integrate the river here.
Their work concluded that four distinct basins contain a similar sequence of deposits that grade from the bottom with (a) material derived only from the enclosing mountains, (b) coarse debris derived from bedrock exposures upstream of the basin edge, (c) fine-grained lake deposits, and (d) unmistakable deposits from the Colorado River. The interpretation is that water rapidly arrived (geologically speaking) in the Las Vegas basin and eventually overtopped a bedrock divide in Black Canyon, thus rapidly filling the basin in modern Cottonwood Valley. The spillover from the Las Vegas basin formed the river through Black Canyon (Hoover Dam area) as it rapidly filled the Cottonwood Valley. Eventually the Cottonwood Basin overtopped a bedrock divide in the Pyramid Hills (Davis Dam area) and spilled water into the Mojave Valley (Laughlin, Bullhead City, Fort Mojave, and Needles areas). This spillover rapidly filled the Mojave Valley, which was large enough to merge with the former lake in Cottonwood Valley, creating a larger and deeper lake. This lake ultimately overtopped another bedrock divide at Topock Gorge, subsequently draining the Mojave Valley and filling the Chemehuevi Valley downstream (Lake Havasu City and Blythe area). This basin was breached by spillover at the Chocolate paleodam, making a final connection with the Gulf of California.

In outlining the sequence of deposits (and the events that created them) the authors provided support for a lacustrine (lake) origin of the Bouse Formation, noting only that it was substantially eroded after the lakes drained. Overlying the Bouse remnants are diagnostic and unmistakable Colorado River sand and gravel deposits that culminated in the southernmost basin about 4.1 million years ago, according to them. They wondered what might have brought the rapid arrival of river water to the Las Vegas basin and turned their gaze figuratively and literally upstream toward the Grand Canyon and beyond. Could some other upstream basin also have filled and spilled? Or was it perhaps stream capture related to headward erosion or karst collapse? The results from the lower Colorado River area only intensify questions for how the upper Colorado River became integrated, but the origin of the lower Colorado River now seems rather certain.

Congratulations to these three for winning this award. The "fill and spill" theory is an exciting development in the understanding of the origin and evolution of the Colorado River. By extension, this also helps to better understand the history of the Grand Canyon. When these researchers wondered what might have caused the relatively rapid arrival of water into these disconnected basins, they figuratively and literally looked upstream on the river toward Grand Canyon. They wondered if basin spillover might have happened there as well. However, the evidence for that is not all that good.

Thursday, July 04, 2013

The 4th Annual Bryce Canyon National Park Geology Festival

Bryce Canyon National Park will host its 4th Annual Geology Festival on July 26 and 27 inside the Park. This will be the third time that have been asked to be involved. You can see an earlier posting here from the 1st festival held in July 2010. Plan your cool trip to  Bryce Canyon and enjoy the greatest Earth on show!

Programs offered are as follows: 

Tuesday, July 02, 2013

30 Year Anniversary of The "Way Too High" Trip in Grand Canyon

Today, July 2, is the 30 year anniversary of a river trip I took on the Colorado River in Grand Canyon that has become known as the "Way Too High" trip. Avid boaters will recall that an immense snow pack in the Rocky Mountains in 1983 (remember those?) came down into Lake Powell "Way Too Fast" necessitating a "Way Too Much" water release from the reservoir, allowing 15 crazy rafters in Flagstaff to commence on the "Way Too High" trip. The river ran close to 100,000 cubic feet per second. To see a link to John Parsons blog about the background of all of this, see here.

To give you an idea of how much water that is, the "flood" that was let down the river last November to restore beaches in Grand Canyon had 42,500 cubic feet per second. The 1983 trip was accomplished in two full and two half days. I usually just tell people it was a three day trip. To go 225 miles in the Grand Canyon. In rowing boats. Camps were made at 24.5 Mile Camp, Ninety-Four Mile Camp, and National Canyon. It was an epic trip in an epic time. 30 years ago today.

 Here is the put-in at Lees Ferry about 2:30 PM on July 2, 1983

The large white ripple upstream is Ten Mile Rock, usually sticking out of the river 12 feet. The reason I took this photo from the downstream position is that the river was moving so fast, that by the time I had my camera, we were past it.

In Marble Canyon after one hour.

Boulder Narrows at 100,000 cubic feet per second (cfs)

Close-up of the big rock in Boulder Narrows

This is what the big rock looks like at normal water levels these days.

Notice the kayakers paddling beneath Vasey's Paradise here on the morning of July 3, 1983.

Note the tiny black dots - people - frolicking on the sand in Redwall Cavern here at a normal water level.

Here is Redwall Cavern on July 3, 1983

Notice the kayaker paddling in the back of Redwall Cavern. Big water. Big, big water.

Hance Rapid scouting view from river left.

The beach at Bright Angel Creek (Phantom Ranch). Note the kayaks pulled up on shore.

The mouth of Bright Angel Creek flooded by the Colorado River.

Hermit Rapid view, July 4, 1983.

Crystal Rapid was the big concern. A hydraulic jump had flipped three huge 33-foot boats a few days before in this hole. You cannot see the bottom of this hole in the photograph. Our rafts were 16 feet long.

Scouting Crystal Rapid on the morning of July 4, 1983.

More scouting.

We'd better just run over the tamarisk trees.

Yep - that's what we did!

Our dory hit a rock or log in Walthenburg Rapid and here Larry Stevens fixes the hole as we stopped near the Garnet camps.

Deer Creek Falls on the Colorado River July 4, 1983. Note the large rafts on the left.

Here is Deer Creek Falls at a more normal flow. It does not normally drop straight into the Colorado River.

One of the most amazing pictures I was able to take on the trip - this is Pancho's Kitchen Camp. Yep - that little slice of shade at river level is the roof of Pancho's Kitchen.

Here is a group setting up camp within the alcove at Pancho's Kitchen at a more normal river level. The roof is not even visible here at the top of the photo.

Enterting the Icebox section of the river in mid afternoon.

A kayaker buzzes past the entrance to Olo Canyon on July 4, 1983. This is normally a 25-foot high fall to the creek bottom.

Here is the a view of that drop in August, 1983. Here the river has dropped to only 45,000 cfs and the rafter can still boat into Olo Canyon. At normal levels today, the river is 100 yards away from here. Even this picture will amaze modern boaters.

The Icebox, late afternoon July 4, 1983.

Our last camp was made inside the mouth of National Canyon. I snapped this picture before the sun went down on July 4, 1983.

Lava Falls on the morning of July 5, 1983. Note that the big hole at the top is completely gone at this water level. It was just a fun v-wave ride - no problem.

Water pours over the Black Rock at the base of the Falls. 

Take-out at Diamond Creek on July 5, 1983 at about 1 PM. My biggest regret was not taking a group picture! My second biggest regret was not getting a photo of the huge rafts that were in ruins below Crystal Rapid. Other than that no regrets!

Young Wayne on a Colorado River trip in 1981. Thanks for reading!