Guadalupe Mountains National Park

Location: Culberson and Hudspeth Counties in western Texas.

Introduction
Located in the high desert of the American Southwest Guadalupe Mountains National Park (Wikipedia page) is like no other park I had ever been too. This was the first national park that I went to since moving to Texas from Pennsylvania. The park has amazing views from atop of the ridges and many hiking trails to get up there. I only spent a few days out here so I only had time to take one hiking trail, it was the geology trail so that will be helpful. The park also contains the highest point in the State of Texas, Guadalupe Peak. The hikes from the basin up to the top of the mountains are hard, typically over 2000 feet of elevation change with the hikes starting at around a mile high. This drastic change in elevation brings with it a drastic change in climates, from a true desert in the basin up to a cooler and more wet environment up on top of the mountains that allows for the growth of a forest. This park is a geologists dream, why you may ask? Well keep reading to find out.

Geology:
Most of the information from this section is summarized from Bebout and Kerans (1993). As I said this National Park is a geologists dream for a couple of reasons. The first reason is the amount of exposed rock, this is typical of many of the western parks because of how dry try are does not promote the growth of much vegetation. The other reason is what has been preserved. Guadalupe Mountains National Park represents a complete reef system from the deep water turbidity deposits up to the more shallow water reef system. If you have looked at the map you may be wondering how this worked since this park is many hundreds of miles from the present ocean. This was not the case during the time of deposition, the Permian, where the ocean came up to the area that is now the park. If you look at this image you will see two shallow water fingers on the western edge just north of the equator. These two fingers represent the two main portions of what is known in the oil and gas industry as the Permian Basin. The more western basin is known as the Delaware Basin, this is where the park is located, the eastern basin is known as the Midland Basin, this is where most of the oil was found. Back to the park during the Permian this reef was building up but unlike modern reefs that are primarily formed by corals the reef that formed the mountains in the park were actually formed by more hard bodied sponges than what we typically find alive today [photo at left one of these sponges taken by author]. These sponges like modern coral secreted calcium carbonate meaning that the mountains are almost entirely limestone. As I mentioned earlier the full reef system can be seen while walking along the trails. This includes many fossils of the reef builders and those that lived on the reef which unfortunately makes it prone to being looted and having fossils hacked out of the rock itself. The limestone is easily dissolved when it comes in contact with acid, this a very good way to test for limestone and is done in most introductory geology labs (see video here), and because of this there are plenty of caves and similar bodies around the area (foreshadowing of a future post).

What makes the geology of the park even more impressive is that it represents a paleotopography [photo at right of El Capitan by author]. This means that if you are standing at the bottom looking up at the top of the mountains it would about the same elevation change as it was during the Permian millions of years ago only it would have all been covered with water. This is the main reason why the entire reef system is preserved since we are looking at the system as it was millions of years ago. So why is all of this visible now? One of the reasons is that after the reef was formed the shallow sea that covered the area went through periods where there were large amounts of evaporation. This leads to large amounts of salt deposits that cover the region on the way west from Lubbock and the rest of more eastern Texas. This area was probably covered during the Mesozoic and the uplift that formed the modern Rockies began to uplift this area as well. Salt dissolves very easily in water and so as the area was uplifted a lot of these salts were dissolved away this exposed the relatively harder limestones in the mountains and allowed the paleotopography to be shown in the park. Of interest to those interested in the history of oil and gas would be what this all means for that field. The oil and gas in the area is typically found in the limestones that are equivalent to those that make up the mountains. Oil would not naturally stay in a porous rock like these limestones but in areas such as the Midland Basin these evaporties form a great caprock which kept the oil from escaping until it could be reached and it made the region rich in oil money which basically created many of the large cities, like Midland and Odessa, in western Texas.

Guadalupe Mountains National Park shows the geology of the Permian so well that it is in fact home two 2 GSSPs. These symbolize the type sections for the Capitanian, the upper most of the Middle Permian, and Guadalupian, or Middle Permian, rocks. This is really interesting and it is exciting in that there are very rarely two GSSPs in one country let alone that close together.

More Pictures All images below are by the author.









Further Reading:

National Park Service's web page on the Geology

Bebout, D.G. and Kerans, C. 1993. Guide to the Permian Reef Geology Trail, McKittrick Canyon, Guadalupe Mountains National Park, West Texas. Bureau of Economic Geology, Austin, 48 p.
(I really recommend this last one if you are going to do the geology trail because it includes stops and talks about the geology of the are. A digital copy can be found here but I recommend buying one from the park when you get there, support your parks!!!)

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