2008
Field Trip
Part 1the Striped Hills just off US 95 near Lathrop Wells (Amargosa Valley)
This is a view of the Striped Hills to the north of US 95 near where it intersects with the main north-south highway through Amargosa Valley:
The rise to the right in this next photo was our vantage point from which to get a better look at the Striped Hills:
These are some of my favorite rocks, upended limestones laid down about 600-million years ago in an inland sea. So, since they were laid down horizontally, how did they get vertical? A bulldozer blade coming up from the southeast, as it were. See that mass of mountains in the next photo? That is the Spring Range, and apparently from this vantage point it would have appeared1 to have ridden northwestward about 50 km along a fault knows as the Las Vegas Valley Shear Zone, which is now inactive. The LVVSZ, as it is known, had an angle to it, it rode northward, and at its front made a turn that the highway follows as it deviates westward (see the faint line below, that's US 95):
The front of this mass of apparently1 moving rock was angled like a bulldozer blade and upended huge chunks of rock in front of it and created the terrain we are looking at:
Although the LVVSZ is now inactive, the Basin and Range tectonics are still active, and this, valley, called Rock Valley experiences a lot of ground motion, enough so that the road through it (on the Nevada Test Site) is hard to maintain.
Where are we? Here are some views that will help locate this knob we are standing on. First to the west is Yucca Mountain with the remnants of the Timber Mountain Caldera to its right:
Next, a little further south than west is Bare Mountain, on the other side of the southern extent of Yucca Mountain. On the other side of Bare Mountain lies Beatty, Nevada:
A little further south still, is the roadside businesses on US 95 in Amargosa Valley (used to be called Lathrop Wells); the Amargosa Sand Dunes are also visible:
The Funeral Range (with Death Valley behind it) and the Amargosa Farms area in front of it:
Straight south there is a nice sand ramp where winds come through a crack and disperse, losing their sand load:
A closer look in that same general direction gives us a faint glimpse of Eagle Mountain, to the left at the southern end of Amargosa Valley:
Getting back to the Striped Hills, look at these holes made by prospectors in the late 1900's (it is hard to imagine these people here on their burros, no roads, no towns, no conveniences!)
The next view would be where we started, with the Spring Range, so we are done here and will now move on to our next stop. closer to the bulldozer blade of the LVVSZ.
Footnote 1: Although it was convenient to picture the Spring Range as a bulldozer blade coming at us to mentally appreciate the forces that shaped the mountains and rocks we were seeing, it is a bit more complicated. The tour guide, Tom Anderson, as co-author with Damian Piaschyk, published a more scientific description of this phenomenon. Apparently the area to the north and west of the Las Vegas Valley Shear Zone was moving to the southeast, and the Spring Range was not, or at least not at the same rate. So effectively, from our vantage point at the Striped Hills shown above, we were being shoved toward the Spring Range, the Spring Range was not shoving itself toward us.
This underscores the importance of understanding the context of the point of reference of the observer. Once when I was rear ended in my car while stopped at a red light the woman who hit me from behind asked me with extreme irritation in her voice why I had backed into her. In her inebriated state, her awareness of her point of reference was faulty.
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Point of Rocks on US 95
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