Sunday, June 6, 2010

Mega road trip - Day 6

Not much driving today, spending the next few days in Moab, UT - a neat little touristy town between Arches and Canyonlands National Parks.  We started the day by viewing some petroglyphs in the area (Freemont Culture dating between around 700-1,300 AD).  What completely amazes and astounds me is that there are complete morons who try to carve their own names over the petroglyphs whenever they're in reach (these are high up and relatively inaccessible).  If it was up to me, assholes who defaced these sacred sites would be shot on site.

Potash Road petroglyphs

Most of the day we spent at Canyonlands National Park.  The Green and Colorado Rivers divide the park up into three main regions - Island in the Sky, Mazes, and Needles.  We were in the Island in the Sky district - so named because it's a mesa isolated except for a narrow neck out onto it.

The views of the canyons and rivers far below are just incredible and pictures don't do it justice.

It's like being at the Grand Canyon but with a lot more hiking trails that aren't down into the canyon, many of the trails at Canyonlands run across the mesa to some interesting places.  Since we have two kids under 10 and temperatures went over 100 F by late afternoon, we only did some short hikes.  The ones above from from the Grand View Point Trail.  We also went to Mesa Arch.

And Upheaval Dome.

Upheaval Dome is geologically interesting being a dome (obviously) about 3 miles across surrounded by folded rocks in an area where the rocks are mostly horizontal.  What happened here?
There are two competing ideas...

The first is that a meteor struck the area some 60 million years ago (after the impact that killed off the dinosaurs some 65 Ma) and created a large impact crater deforming the rocks which rebounded upward into a central dome after the impact.  What we see at Upheaval Dome are rocks that were once buried a mile underground when the crater formed and exposed by erosion.
The second idea is that Upheaval Dome formed as the result of a salt diapir.  There is a thick layer of salt down below the rocks of Canyonlands that formed from the evaporation of a Permian Period sea.  Salt is less dense than the overlying sedimentary rocks and their weight pushed the salt up as a "plug" or diapir into the overlying rocks deforming them into a dome shape.  We see the deeply eroded remnants of that structure.
While not as sexy, I think the second idea is the most reasonable.  However it formed, it's an incredible structure to come upon in the area - completely out of place.  You can view it in Google Maps satellite view here.

After hiking half the day in the hot, dry desert, we were ready to return to the hotel for a dip in the pool.

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