Saturday, June 23, 2012

Seven Days of Geology and Hiking on the Colorado River in Grand Canyon

I just completed my 7-day raft trip in the Grand Canyon and am pleased to share some photographs and stories about the trip. This posting is not meant to be a comprehensive account of the trip, as there are too many things that happen on a trip like this. Rather, I like to pick a few choice stops and write at length about them. If you would like to read about other aspects from previous trips, scroll down on the right hand side of this page to My Blog Archive. The months to peruse are August and September, 2011; September, 2010, September, 2009, and September, 2008.

This trip included nine members of the Arizona Hydrological Society, as well as eighteen other geology enthusiasts. Some of these eighteen had no idea that geology could be so interesting but a place like the Grand Canyon makes geology fun and it comes easy to anyone with a little effort.  (My next geology class at Grand Canyon will be a 3-day Rim-based classroom and short hikes adventure called "Geology on the Edge", offered by the Grand Canyon Field Institute. Check out the details at this link and click the "On The Edge" button.

I hope you enjoy the virtual ride on this years 7-day Grand Canyon rafting trip!

Day 1

My geology-themed rafting trips are known for their short hikes to interesting places. Here, after traveling only 200 meters on the river, we stopped for a hike to an overlook along the Colorado River. The Vermilion Cliffs loom above the river in the right background. The photographer is standing on the Shinarump Conglomerate Member of the Chinle Fm.

Within the Shinarump Member are numerous and large petrified logs. This one has an oxidized red "halo" around it. Much of the Cold War uranium for bombs was obtained from such oxidized sources, which are known as "roll front deposits".

The old Mormon dugway can be seen running through talus that lies on top of the Moenkopi Fm.

Much of the river in the canyon is calm water. The Colorado is known as a pool and drop river with long stretches of pools interrupted by steep rapids.

Day 2

Entering the Redwall Limestone section of Marble Canyon. John Wesley Powell named it Marble after the polished limestone found next to the river.

Since my last trip, a new fan of debris has developed into the river channel near river mile 30. a huge thunderstorm last fall brought this material down the side canyon.

Vasey's Paradise is a wonderful spring that issues from a cliff of Redwall Limestone. It is located near river mile 32.

Here is a group photo shot inside Redwall Cavern. We had a very congenial group that laughed and played and learned the whole way!

Hiking a short way up to the "rapids" on the Little Colorado River (river mile 61). The water originates 13 miles upstream from the confluence at Blue Springs, the largest spring in the state of Arizona. The color of the water comes from the way limestone is dissolved in the water as it comes through caves.

Riding the "rapids" with a life jacket. These travertine dams form when the spring water releases CO2 after exiting the spring. The water is quite warm.

The Little Colorado River in the bottom of the Grand Canyon

Scenic reflection on the Colorado River looking upstream from the Little Colorado River confluence, June 11, 2012.

... A Collared Lizard Interlude

This collared lizard (Crotaphyyus collaris) used a lack of motion to "hide" from our group as we walked by it at the Little Colorado River.

They are fantastic reptiles that often run in a bipedal fashion across the desert floor

The lizard is resting on the Tapeats Sandstone

And allowed me to photograph it from every possible angle

Day 3

One of the best geology hikes on a Colorado River trip is up Carbon Creek Canyon at Mile 64. Here our group is negotiating a large boulder in the floor of the canyon.

One of the highlights of the trip is seeing the Butte Fault about one mile up in the canyon. Here the Tapeats Sandstone i upturned 90 degrees from its original horizontal position. The fault shows many periods of activity beginning in the Precambrian and last moving during the Laramide Orogeny about 70 million years ago. That is when these beds were upturned. Important to remember is that when these beds were faulted to this position, the rocks shown were at least still 2 miles in the subsurface, maybe more. Erosion of the Grand Canyon has exposed what was previously bent.

Hiking along a quiet stretch in the Grand Canyon

Day 4

Much farther down the river we stopped at Blacktail Canyon at river mile 121. Here is fantastic exposure of The Great Unconformity.

View out of Blacktail, a narrow slot canyon

Close-up of The Great Unconformity with Vishnu Schist below and Tapeats Sandstone above. Quartz clasts rest right at the surface of the unconformity, which represents 1,200 million years of time. Note the small dendrtites that seem to emerge from the quartz clasts on their top side.

A small scale channel within the Tapeats Sandstone just above the unconformity. These channels were likely cut as the waves of the Tapeats Sea washed back across the surface.

View of lunch at the mouth of Blacktail Canyon with Conquistador Aisle stretching away three miles in the background

Our trip leader Carolyn shares a laugh on the river

Day 5

The group checking out Bronze Black's informative river map while traveling down the river. You can order a copy of this map here.

Havasu Creek at river mile 157 is a lush oasis in the desert. This is the second largest spring in Arizona.

While making a comfort stop on the white sand beach, we observed this interesting trackway

I am guessing that this was made by a river otter or a muskrat

Interesting pictograph panel at Whitmore Wash, site of our 5th nights camp

Here is the impression of an interesting invertebrate trackway in the Bright Angel Shale near Whitmore Wash.

It looks like the medium is soft sand, yet this is a rock that has been hardened through 515 million years of earth history

Day 6

While on the river, we get the opportunity to "follow" certain sedimentary layers that change thickness and color along the length of the river. This is the so-called "rusty brown dolomite" a layer within the Bright Angel Shale that we first noticed way upstream near Elves Chasm. Here in western Grand Canyon it was much thicker that when fist observed.

The Black Ledge lava flow (black, center) filled the channel of the Colorado River for at least 86 miles when it was erupted some 500,000 thousand years ago

Day 7

Final morning on the boat, our group assembled for one last picture. Having a predetermined theme for the trip meant that everyone came to it with similar goals. This is really the only way to undertake a river trip of such length. It does not need to be geology, but earth history is a dominant theme encountered in the Grand Canyon.

Our fantastic crew! Paul, Tom, Carolyn and Amity. Thanks to Canyoneers for providing such hard working and freindly guides.

Wednesday, June 06, 2012

The Tranist of Venus seen from Flagstaff Arizona June 5, 2012

Regular readers of this blog will recall that we sought out an isolated (but named) point on Grand Canyon's South Rim for the recent annular eclipse. Since the park became so overwhelmed with eclipse watchers, I wanted to experience in as natural a setting as possible. So when an even rarer event known as the transit of Venus occurred on June 5, we wondered deeply where we would go to view it. I very much like non-social settings for events such as these, but I also don't necessarily feel attached to any one particular kind of location. I try to let the moment speak for itself in these kind of situations.

I first targeted the summit of Mt. Elden which sits high above above Flagstaff at the elevation of 9,299 feet. There is a road to its summit and it would have provided a clear and unobstructed western view. However, the windy conditions of the day really precluded that. So when the US Naval Observatory in Flagstaff announced that they would hosting a "transit party" I thought, "Why not." So, I loaded up my camera, filters and tripod and headed west on old Route 66.

The US Naval Observatory, Flagstaff Station (USNOFS) is located on top of a relatively young cinder cone about 4 miles west of Flagstaff. The observatory is set among a well-managed (i.e. thinned) Ponderosa pine forest.

The view from the top of the cinder cone and the observatory is spectacular! Looking to the north you can see San Francisco Mountain, a collapsed and eroded strato volcano that last erupted about 440,000 years ago. As you can see, northern Arizona was blessed with fantastic viewing conditions for the transit (and explains why the Navy chose this site for the USNOFS. I heard from friends in Florida and Massachusetts who were denied viewing because of overcast and my heart goes out to them for not seeing the transit as we did.

Here is a view of the sun at 3:00 PM MST as I approached the observatory. Note that Venus is not yet visible as 1st contact (when the planet first touches the outside disk of the sun) did not occur until 3:04 PM MST. I used my Canon Mark II 5D camera on a tripod with a 300 mm Image Stabilizer lens and 6400 ISO. A solar viewing filter was placed in front of the lens to allow shooting into the brilliance of the sun.

The view at 3:35 PM MST after Venus passes 2nd contact - when the entire disk of the planet is inside the disk of the sun. You can see Venus as the small black dot in the upper right of the sun. This will be about as spectacular as it gets since 300 mm lens is about as small as can be used to see something like this.

Attendees using the various instruments that were set up on the lawn outside the USNOFS

This photo was taken more than one hour later (at 4:40 PM MST) and clearly shows the planet making its way across the disk of the sun

There are numerous methods employed to safely view the sun and here is a reflective technique. The dark disk of Venus can easily be seen against the whitish appearing sun from this telescope. Note the faint splotches to the left of Venus - these are large sun spots that can bee seen when viewed this way.

View of the transit of Venus at 5:15 PM MST from the US Naval Observatory - Flagstaff Station

One of the highlights of watching the transit from the USNOFS was seeing it through the Clark 5-inch refractor telescope, made expressly for the USNO for the 1874 and 1882 transits. In 1874, this very telescope was used in Peking, China to observe the transit, while in 1882 it was sent to Wellington, South Africa. Eight of these were ordered for use in those two transits and six of them are still owned by the USNO, with this one permanently housed at the Flagstaff Station.

An astronomer recalibrating the viewing of the 5-inch Clark refractor

The engraving on the tube reads: "A. E. Clark & Sons, Cambridgeport, Mass." There was a long line for folks to view the transit through this telescope, even though video monitors showed it larger elsewhere on the grounds. A sense of history and rarity permeated the event.

Finally, at 6:25 PM MST, the transit reached its zenith, meaning that it completed half of its distance across the suns disk. Compare this to the first photos and you can see that Venus appears to travel from the top of the suns disk to its lower right. The entire transit lasted for 6 hours and 40 minutes and I saw 3 hours and 30 minutes of it.

A viewer watches the transit through a pair of strong binoculars with a filter attached. This was perhaps the best view seen of all the methods available.

My tripod setup for my camera. When the transit began at 3:04, the lens was pointed almost overhead but by the end of the day it was much more horizontal.

My final shot of the transit taken at 6:30 PM MST. The sunset yesterday in Flagstaff was at 7:38 MST meaning that there was still more than one hour left to view the transit before it dropped below the horizon. Look for Venus soon as the morning star in the eastern sky, as it continues in its orbit around the sun.

A big thank to the staff and volunteers at the US Naval Observatory - Flagstaff Station for opening up their facility and providing a world-class event that will not be seen on planet earth until 2117. Will blogs like this be as obsolete as the sailing vessels that took earlier astronomers to the 1874 and 1882 transits of Venus? Likely, it will but let's hope that this tiny narrative will be read by some future reader who might wonder about the June 5, 2012 transit of Venus!