Delbert Dowdy
McDonald Observatory Davis Mountains
N 310 51.258’ W 1040 50.645’
Elevation: 4937’
Content:
McKittrick Canyon is one of the best ways to personally explore the Capitan Reef area. Several million years of reef activity is revealed in the canyon. This is the best preserved ancient reef complex in the world. Before reaching the visitor center for the canyon we stopped along the highway outside the canyon to hear an explanation of the basic structure of El Capitan. We took a short break at the main visitor center and then proceeded to the McKittrick Canyon visitor center. The temperature was climbing as we approached the early afternoon. Temperatures were near 100 degrees each day.
After a brief description of what we could expect in the canyon, we set off for the river bed at the bottom of the canyon with those people physically able to make the journey. The path was covered with loose and uneven rocks which required much more attention to where you stepped. At the bottom of the canyon was a dry riverbed about 10 meters wide that was covered with rounded pieces of white reef limestone that was full of fossils. The reef material is unlike any modern reef material. Instead of being made of coral, it is made up of stomatolites and diatoms. There were beds of limestone and sandstone that lined the walls near the riverbed. The limestone was generally light colored and the sandstone generally dark colored. Much of the surrounding rock was flat where one could clearly see the layering. In the rock cliffs you could see hollows where the water had at one time flowed. In several locations one could see where large and small pieces of the reef material from high up had fallen down the slope and were slowly covered by layers of sandstone. This caused soft sediment deformation which caused uniform thickness layers to be laid down on a slope rather on a horizontal surface.
After returning to the McKittrick Canyon visitor center, two groups split off with one group going on the lower nature trail and my group climbing the relatively steep path toward the lowest portion of accessible exposed reef. All of McKittrick Canyon is contained in what is called the forereef just under the actual reef material. Although the path has been improved, it was still steep, uneven, and covered with loose rock that could easily move underfoot. The rock along the path changed from the lighter color sandstone to a darker limestone. The darkness comes from the organic material trapped in the shells that make up the limestone. This is the precursor material to making oil. Although we were able to climb to the top of the canyon wall, we did not have enough time to proceed to the actual reef material. We were approximately on the same height level as the reef material. Reflection:
The view of the mountain was spectacular. From the top, one could get a better view of the surrounding area and see where the lagoon of the reef system was located. This was clearly a highlight of the trip and to have a knowledgeable geologist there to explain it all made the area come alive.
Saturday, June 3, 2006
