Friday, April 27, 2012

Photo's From My "Exploring Escalante" Trip

I was leading a trip up in the Escalante Canyon region of Utah during the week of April 16. Many members of our group contributed photographs. Have a look at them and the captions will explain much of what we saw. Thanks to photographers John Grahame and Kate Killibrew.

The Cottonwood Canyon Road has been washed out since January so we took the Skutumpah Road instead and got a view of Bull Valley Gorge. This is a narrow slot canyon cut into the Navajo Sandstone.

Our first hike was to Calf Creek Falls. This little oasis is a gem in the red rock country. John's photograph here is on the approach.

And a clear view of the 100 foot fall

Vandalism on a rock art site above the Escalante River

But there was lots more that was untouched

This pictograph is called 100 Hands but requires a big climb to access it

Enjoying the view
On the trail
Photographing the rock art
Another great panel just above the Escalante River

John G. the trusty assistant

Wayne and Carolyn at dinner

Thursday, April 26, 2012

New Exhibits at Grand Canyon National Park

Regular readers of Earthly Musings know of the fantastic changes happening at Grand Canyon National Park. In October, 2010, the Trail of Time was dedicated. And in January of this year, the 100th anniversary celebration of the Kolb Brothers historic river trip was commemorated with an exhibit at Kolb Studio.

The National Park Service has installed new exhibits at the Visitor Center and Helen and I toured them recently while visiting the South Rim. Here is the press release on the new exhibits.It is definitely worth a look when you next visit the park.

Monday, April 16, 2012

Exploring Canyonlands in Utah - Part 2

Here is the continuation of the posting for my five-day trip to Canyonlands. This includes photo's and discussion from days 3, 4, and 5.

On Wednesday we made the 2.5 mile hike along Negro Bill Creek to Morning Glory Arch. It is an impressive span in the Navajo Sandstone.

View from beneath Morning Glory Arch. While we were here, a tour group arrived on top of the arch with the intent of rappelling down the 120 vertical feet. The rope thrown over the edge nearly hit our party!

One of my favorite places on all of the plateau is Fisher Towers. These spectacular monoliths protrude from a mesa with the strata tilted on the east side of the Professor Valley salt dome. The cap rock is Moenkopi Formation and most of the tower composed of the Cutler Group. This is the same stratigraphic horizon as the layers seen in Monument Valley. Bet here, the deposits were derived from the near flank of the Ancestral Rocky Mountains and thus they are much coarser-grained and undifferentiated as individual formations. A true geologic "must see."

Pointing out something or another to the group. I have to say to say that it was such a pleasure to travel with folks who were keen on learning all they could about geology.

Day 4 say us visiting Arches National Park and we took an early morning hike up to Delicate Arch. That is the five of us standing beneath the arch.

Before lunch we walked on the Sand Arch Trail into these fins of Entrada Sandstone. They have formed along joints that run parallel to the Salt Valley diapir, a salt dome that punched through the strata.

It is along these narrow fins that many of the arches are formed. This is Partition Arch along the way past Landscape Arch. These thin walls, in combination with the presence of an aquaclude in the lower  Dewey Bridge Member of the Carmel Formation, make for the perfect setting to form arches. See here.

Day 5 and time to head back south to Flagstaff. We stopped by the Needles District of Canyonlands National Park. Here is a view of the Needles, carved into the Cedar Mesa Sandstone.

From left to right, Ed H., Georgia; Wayne R., Arizona; Howard C., Tennessee; Kent C., Arizona; and Inge H., Arizona

Discussing the paleoclimatic implications of a fossil pack rat midden. These little piles of poop help to preserve a record of the Ice Age climate in the Southwest. Pack rats (genus Neotoma) only travel 100 meters or less to collect material for the nest. Since the climate of the Southwest is perfect to preserve the specimen, the plant material that is cemented into the amberrat gives a first hand account of what was growing here up to 50,000 years ago. Wetter climates then meant that vegetation communities were depressed almost 1,500 feet lower than they are today. Imagine Ponderosa and Lodgepole pine growing in the Needles!

Our final stop was at the Goosenecks Overlook along the San Juan River. I've completed many trips in my years in the Southwest through here and it would be nice to offer a trip down here again for geology enthusiasts again! Thanks for reading.

Sunday, April 15, 2012

Exploring The Canyonlands in Utah - Part 1

Last week I was up in the Canyonlands area near Moab, Utah leading a small group of enthusiasts with the Museum of Northern Arizona Ventures Program. We had an excellent time with all of us being veteran geology buffs excited to see the world-class stratigraphy that this area affords. One of my participants, Kent Colbath, is a great supporter and volunteer at the Museum and came along with his camera on the excursion. Long time blog readers of Earthly Musings will be familiar with my photography here, but this time I thought it might be fun to see how one of my participants viewed the places visited on our five day trip. I will do this in a few different blog postings and here are the first two days of our trip. Have a look at what we saw and learned about.

Our first stop on the way to Moab was Monument Valley. Here we took a 3.6 mile hike around Mitten Rock, seen on the left. Monuments here are capped (top to bottom) by thin outcrops of the Triassic Shinarump Conglomerate and Moenkopi Formation. The major part of the cliff is composed of Permian  De Chelly Sandstone with lower aprons of the Organ Rock Formation. This sequence would be observed many times during our week in Canyonlands. The floor of Monument Valley and not visible here is the Cedar Mesa Sandstone.

After passing through Mexican Hat, Utah, we saw the Raplee Anticline where the Pennsylvanian Halgaito Shale (top red) and Honaker Trail Formation (lower red and gray) create a kaleidoscope of color along the San Juan River.

Our first day on the ground took us to Island in the Sky in Canyonlands National Park. Here is a NASA image of Upheaval Dome, an odd structure located atop the plateau. If you look very closely in the upper left, you will see the paved road that crosses the upturned Navajo Sandstone ridge and enters one of the inner rings of the structure.

Our first stop on the ground was Whale Rock, seen in the foreground. Here you can see a semi-circular outcrop pattern within the Navajo Sandstone. This is the outer ring of Upheaval Dome. Studies in the last 15 years have shown pretty good evidence that this is the result of an impact crater from a meteorite that hit the earth in higher (now eroded) rocks back in the Cretaceous Period (about 90 Ma). Another popular theory that is now mostly discredited is that the dome formed from the movement of underground salt. While on Whale Rock, I showed our small group a series of three NPS pamphlets that explain the formation of this structure. The first one was from 1983 and highlighted the salt some theory with only one sentence at the end dedicated to the impact theory. The second pamphlet was from 1991 and contrasted the two theories equally within it. The last pamphlet is from 2009 and the impact theory was given the vast majority of space in it. Inadvertently, I have assembled a crude history of thought on Upheaval Dome!
We hiked about a mile to two overlooks that allowed us to peer into the core of Upheaval Dome. What a mess! The impactor likely hit rocks that were about 4,000 higher than this. Subsequent erosion has removed the overlying material.

Beautiful Indian paintbrush on the trail near Upheaval Dome

Later in the day we hiked out to Grandview Point, the southernmost projection of the Island in the Sky. On the way back, Kent took our picture with the La Sal Mountain laccolith in the distance. See two of my previous blogs on lacccoliths here and here.

With a positive thinking group, we drove down the Shafer Trail off the rim of plateau. This old uranium haul road was a thrill and a half! Our van made it too.

Our van on the lip of the Shafer Limestone. This is near the place where Thelma and Louise drove off of the "Grand Canyon" in the famous 1991 movie.

Here I am pointing out the geology at the end of a fantastic day of geologic touring!