With the conclusion of the conference, it was time for a field trip. Dr. Ray Beirsdorfer conducted a guided tour of the geology around and in Red Rock Canyon.
|Planning The First Stop|
We gathered together a caravan to head for the first stop. I rode the car of the very friendly and kind Dave and Candace from San Diego, with Oren, from someplace in New England, as I recall. In the picture above, Oren is standing next to Dr. Beiersdorfer, and Dave is just behind and between them.
|Then Drive Until You See Some Rocks|
Once we were moving, we headed south and west, and were joined by Moe in the Pink Beetle.
Our first stop was in front of an interesting looking structure. Since several of the people on the tour knew whose house it was, Dr. Beiersdorfer confirmed the identity of the owner. It was an appropriate place to start the TAM 2 geology field trip, and I'm glad that I got a look at the house, but as for the identity of the owner, I'm not going to teller.
|Discussing the Arden Domes|
The geological reason for the location of the stop, though, was to see the Arden domes, visible in the picture above. Dr. Beiersdorfer began with a brief overview of geology basics, and then described the history of the rocks we were seeing.
In the Cambrian era, the land mass which would become North America was in the southern hemisphere, was rotated 90 degrees clockwise from where it is today, and was joined into a supercontinent with the present west coast of North America adjacent to the eastern coast of Antarctica.
|Rapt Attention From The Group|
The Arden domes were thought to be good places to drill for oil, because they formed an impermeable cap under which the oil could be trapped. Many wells have been drilled in search of the oil, but none have been successful.
|Next Stop, The Gypsum Mine|
The type of geology in which Las Vegas sits is known as a "Basin and Range". During the Mesozoic era, the floor of the Pacific was being subducted under North America. This caused a range of volcanoes to form in the west, and thrust faults to push up large blocks of sedimentary rock to the east. In the Cenozoic era, the subduction had ceased, but further faulting has caused the basin between these mountain ranges to fill with material, due to landslides and other processes.
|Some Beautiful Desert Scenery|
Along the way to Red Rock Canyon there were a number of very striking hills to take pictures of. The late afternoon sun was great for bringing out the details of the rock's structure.
|Red Rocks At Last|
At our third stop, we began to see the red rocks for which our destination was known. Dr. Beiersdorfer explained that the yellow and red rocks were fossilized sand dunes, formed about 160 million years ago, during the Jurassic period, when the area was a Sahara-sized desert. These formations stretch across several states. In Nevada, it is known as the Aztec Sandstone, and in Utah, the Navajo Sandstone. The difference in color between the yellow and the red is simply due to slight variations in the mineral composition of the cementing material holding the sand grains together.
|A Fault Lies Behind These Hills|
The grey hills in the background are actually older than the Aztec Sandstone underneath it, dating from the Cambrian Era. This reversal of the normal geological order is due to the Wilson Cliffs thrust fault lying between them, where the older rock has been pushed over the top of the younger.
|But It's Not My Fault|
Armed with all of this information, we were now ready to enter the canyon itself and get up close to the red rocks.
|Red Rock Canyon Visitors' Center|
But first, we made a quick restroom stop at the visitor's center. The original plan had been to stop at the center for a longer time, and see some of the information there, but we were a bit behind schedule and decided to make the most use of the remaining light.
|Red Rocks Much Closer|
At the next stop, labeled "Calico #1" on the map, we had a chance to walk around and examine the rocks closely.
|Crossbedding Of Ancient Buried Sand Dunes|
Here was an example of cross-bedding, where different layers of sediment were deposited at different angles over time. In the picture above, and the next two, you can see the texture that this created. I had heard about crossbedding before but had not seen it.
According to Dr. Beiersdorfer, the surface of the crossbedded rocks is a vrnish layer on the surface, with manganese as a primary component. It is also thought that bacteria may play a role in its formation.
|Wyvern Tries On A Renata Pose|
We spent about a half hour at this stop, climbing down as far as we dared, depending on skill level and type of shoes worn. Wyvern climbed up on an outcrop, posing for pictures, but claimed that it was too cold for the full Renata pose.
|Arcticpenguin Supports A Cause Close To His Heart|
From the vantage of our next stop, we could see most of the length of the canyon. The daylight was starting to fade, so we spent only a few minutes there taking in the broader picture of the canyon's past and present.
|Handprints On The Wall|
Before we left, we had time to tour the very old graffiti on the canyon walls. First, we stopped to see the pictographs left by the Anasazi over 800 years ago. The sign at the site says that the handprints (look carefully at the center of the picture above) were probably made using a "paste solution of iron oxide and water".
|Carvings From Long Ago|
Our final goal on the trip was to find the petroglyphs that were in the area. Dr. Beiersdorfer knew approximately where they were, but we were going to have to search around. It turned out that there was a much easier path to the carvings, but we carefully avoided it, and went crashing through the brush and cactus in every direction until someone finally found what we were looking for. Then, we had to stumble through more brush and cactus in an attempt to get to them. The walk back to the cars after a few minutes viewing time was on the nice, well-marked path.
It was nearly dark by now, and so we completed our circuit of the canyon and headed back to Las Vegas. On the way, we passed by Penn's house, The Slammer. I attempted to take a picture, but it was a hopeless task, speeding along in the dark. I got a dark frame with a few blurred lights.