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.

1 comment:

Gaelyn said...

I'd be interested in signing up. Just about the right time before the season starts at the NR. How about an Escalante trip for our training? ;)