Monday, September 27, 2010

My 2010 Grand Canyon Rafting Trip

Rafting the Colorado River through the Grand Canyon is truly one of the greatest adventures a person can take. Although widely known for its whitewater rapids, the river is calm for 91% of its length in the canyon, providing a glorious "highway" of desert scenery and canyon geology. Each year I offer a 10-day trip down the river and here are a few of the pictures I took on this years trip.

A river trip in Grand Canyon starts at historic Lees Ferry, where the Kaibab Limestone comes to the surface. You can see the top of the Kaibab Ls. as the white layer above, capped by the reddish Moenkopi Fm. Amazingly, this is the same layer that all visitors to the North and South Rim stand on when they visit the more populated parts of the national park. From Lees Ferry, it is 88 miles by river to Phantom Ranch and the river cuts down 650 feet. So how come the canyon is 5,000 feet deep at Phantom? The answer is found in the way the rocks themselves are arched up to the south, providing most of the depth of the Grand Canyon.

Marble Canyon is a photographers paradise and was named by John Wesley Powell for the way the Redwall Limestone appears like polished marble when abraded by the river. Here are a series of caverns found in the Redwall in Marble Canyon. These caverns formed by groundwater solutioning before the canyon was cut. An exciting new proposal by Dr. Carol Hill suggests that a portion of the Colorado River may have been positioned with the collapse of such caverns.


Participant Bill Merrow (on his third consecutive trip with me in Grand Canyon) looks at the grave of Peter Hansborough near Eminence Break. Hansborough lost his life in the 1889 Stanton Expedition (which did not use life jackets). His body was found in an eddy near here and he was buried beneath this small cliff.

The inscription above the grave.

The moon rises over the east wall of Marble Canyon. On this trip we had many starry nights after the moon set behind the cliffs.

A beautiful view downstream in Marble Canyon from the Eminence Break trail. The river was emerald green in the first 62 miles of our trip.

An oar powered boat enters President Harding Rapid at mile 44 (mileages on the river are measured from Lees Ferry which is mile 0). The 1923 Birdseye Expedition laid over here when they heard the news that President Warren Harding died.

A sandbar is framed by reflections in the river. Such bars were once more common along the Colorado River but most sediment is now trapped behind Glen Canyon Dam - the river in Grand Canyon is often sediment starved. That is why artificial floods are sometimes created with releases from the dam. These floods are controversial because water and power managers are loathe to release stored water that does not make power. However, the native fish require the backwaters near these sandbars to reproduce. Discussions about dam management and native species are an added attraction to these educational trips.

Long before there were advanced forms of life, algae ruled the world. Here on the Carbon Creek Beach are the fossil remains of stromatolites, ancient algae that flourished in a warm sea some 800 million years ago. Here we completed a 4-mile loop hike to see the deposits where this algae can be found.

Along the Butte Fault in eastern Grand Canyon are rocks belonging to the Chuar Group. They are as colorful as the much younger Chinle Fm. but formed in shallow marine environments about 800 million years ago.

Bob, Howard, Beth, and Bill pose in front of a colorful (and highly faulted) wall of the Chuar Group. Very few visitors to Grand Canyon ever see these rocks as they are only exposed away from the river in a remote part of the canyon.

This is where the Colorado River crosses the Butte Fault at Tanner Rapid (mile 69). The dark Cardenas Lava has been faulted 1,100 against the reddish Dox Sandstone. Multiple periods of movement are documented on this fault including Precambrian extension (shown here) and Laramide compression (which created the East Kaibab monocline).

After running Hance Rapids, the river enters the Upper Granite Gorge, a fantastic and deeply cut inner canyon along the river.

One of the exciting "discoveries" on this years trip were these very unique and rare rock types that we visited during lunch at 91 mile Canyon. The rocks are dark green in color and their mineralogy suggests that they were part of the earth's mantle that got caught up in the folding and deformation of the Vishnu Schist.

Howard Capito sits on these ultra-mafic rocks in 91 Mile Canyon.

One of Grand Canyon's greatest secrets (revealed repeatedly as you travel down the river) is how many of the side canyons have waterfalls and clear running streams. Elves Chasm is always a delight to river runners but just outside this little grotto are massive deposits of travertine that document that this little stream is just a tiny remnant of what used to be inside the Grand Canyon. Ice Age conditions here were wetter and provided a lot more groundwater for springs than are now observed.

I love seeing ancient topography preserved in the modern landscape! And just downstream from Stone Creek (mile 132) is an excellent example of where ancient islands in the sea became buried by beach sand (Tapeats Sandstone). In the photo above, see if you can find the island mass and the deposit that buried it? If not, look at the next photo.

This is a close-up view of the same photo and includes a red line that outlines the Tapeats Sandstone. Note the angled beds of Shinumo Quartzite below this. The bottom red line marks an ancient surface (some 525 million years ago) that existed on an island within the Tapeats Sea. As sea level rose sand was progressively deposited on this surface. Note on the far right that the islands top was not buried in sediment until Bright Angel Shale time. This is living geology!

Here is another island topped by Tapeats Sandstone farther downstream on the trip. The island this time is composed of Bass Limestone (dark, slightly angled cliff) and you can see the lighter colored and thinly bedded Tapeats Sandstone on top of it.

Here is a view downstream on the river at mile 134, where a massive slide came down the walls of Grand Canyon and filled an old channel of the Colorado River. The slide material is light in color compared to the darker old walls of the canyon.
Here is a picture with lines drawn to help you see the old channel and walls of the Grand Canyon.

Some of these slides were powerful enough to run-up onto the opposite slope across the river. Note the rusty brown beds sitting atop the dark brown Tapeats Sandstone here. These rusty brown beds originated on the other side of the Colorado River (right) and slide progressively up onto the southern walls of the canyon (left). This deposit is called Poncho's radical run-up.


We were able to stop and hike in Matkatamiba Canyon where a fantastic limestone amphitheater awaited us.

Bighorn sheep abound in the Grand Canyon and on this trip we saw at least 30 of them at close range. They are sure footed in this rocky terrain.

Our group scouting Lava Falls from the right bank.

Cactus family at the Lava Falls scout.

Here is a view of the rapid on the morning of September 19.

While we were scouting and taking pictures of the rapid, a group of kayakers came through and we were able to watch them.

Imagine what it must feel like to be in such a small craft up against these big waves.

They all did really well though and it was obvious that they were not intimidated by the white water. Scared most likely but not intimidated.

Almost buried completely in huge waves.

Enjoying the show.

And then someone entered the rapid on a paddle board!

Wow!

We had a great run in the rapid in our 38 foot long boat. Downstream from the falls, we saw evidence for a great outpouring of lava into the river channel. This is one of the most fascinating parts of a Grand Canyon river trip. The lava starting flowing about 720,000 years ago and the history of these flows is still written on the walls of the canyon.

Cooling fractures in a wall of basalt (early morning light).

Across from Whitmore Wash (mile 188) is an outburst flood deposit. On at least five occasions, lava dams that had formed across the channel of the river were catastrophically destroyed and huge floods rampaged the lower Grand Canyon. Here is a picture of one such deposit sitting on top of a previously emplaced flow. Note the large house-sized boulders within the deposit that dip from left to right. These have been interpreted as huge foresets - essentially migrating sediment that is being pushed downstream during the outburst flood.

We camped that evening near Pumpkin Spring and above the camp was a very unusual looking deposit so I went up to investigate. It was composed almost entirely of basalt lava rock and sand. I thought to myself, "What conditions would only make a deposit of lava rock?" Outburst floods was the answer.

Here, Beth Rambikur gives scale to this likely slackwater facies of an outburst flood deposit.

Morning light on the walls of the lower Grand Canyon.

Group shot of the 2010 trip at Travertine Grotto.

Bill Merrow.
Laura Zambrano and Ed Hibbard.

Clay Seaman.

Nancy Seaman.

Howard Capito.

Dana Wingate.

Jeff Eorio.

Our guides Jamie Townsend and Brandon Green.

Vivian Ross, who celebrated her birthday on the trip.

Brandon (rear), Tedi Johnson, Delores Manburg, and Nancy Seaman.

Dana and Audrey Wingate, and Laura and John Zambrano.

On the last day of the trip we had floated through almost the whole of Grand Canyon and the normally red Supai Group had changed into a whitish limestone. This documents that ancient rivers were present in the eastern part of Grand Canyon but eventually entered the sea and marine environments towards the west.

The newest deposit in Grand Canyon - the Lake Mead Formation. Ten years of drought have lowered Lake Mead such that the river has reclaimed much of the lower Grand Canyon. Here the river has incised into lake deposits that are now 40 feet high.

The new take-out at Pearce Ferry that was the location of the end of our river trip. It was a great trip with good weather and fantastic people.

5 comments:

Johnny Montezuma said...

YEA! A home run ball! Great post, Wayne. I have been waiting for this one for awhile and you really delivered. Most Excellent! I especially love your photos of the participants. Your geology is, of course, spot on, as always and brings new insights to every excursion. But you added a great new human element to this post and it's much appreciated. Keep 'em coming, Sir! Cheers, jm

Gaelyn said...

OMG Wayne, this is fantastic. Someday. Instead I finally looked down on lava falls from Tuweep.

Dusty said...

Well, another year, another float trip. Same but different trip from last year. Congratulations on keeping Ed Hibberd mostly in the boat, and keeping Bill Merrow mostly under control. I've heard Bill's version of the trip 3rd hand. I sorry to hear there was no 3rd crewman, I guess that's the economy?
Gary RYbka, [2009 float trip alum]

Canyoneers, Inc. said...

We at Canyoneers River Rafting Company enjoy working with Wayne and having you passengers that are so enthusiastic about Grand Canyon's geology and ecology. Thanks for the great photos and writing, Wayne.

The reason there wasn't an additional crew person this year was because the trip was at capacity, and Brandon and Jamie are senior river guides and we knew they could handle it. In other words, it allowed one more passenger to go that otherwise couldn't.

canyonwren said...

Great posting,hope you dont mind, I tweeted it and also sent it on to Lynn at GCRG and AzRA to share with guides, some great geology info in and with beautiful photos.