Comanche Lookout EarthCache

Comanche Lookout Park

Comanche Lookout Park is a 96-acre public park owned by the City of San Antonio and is the fourth highest natural point in Bexar County with an elevation of 1,340 feet. This escarpment, or ridge of rock, straddles the southeastern edge of the Edwards Plateau and the western edge of the Blackland Prairie.

The escarpment, or hill, making up the bulk of Comanche Lookout Park was created about 15 million years ago during the Miocene epoch and was caused by the uplifting of the Edwards Plateau and the subsidence of the Gulf Costal Plain during an earthquake. But don’t worry, this fault zone is not active today, and Bexar County is considered one of the lowest-risk zones for earthquakes in the United States.

The Edwards Plateau is commonly referred to as the “Texas Hill Country” and covers approximately 36,680 square miles. It is bordered by the Chihuahuan Desert to the west and the Great Plains to the north. It includes a vast range of plant and animal life and is considered one of the most biologically diverse regions in the nation. Vegetation is primarily a mixed low woodland dominated by Live Oak. Most of the Edwards Plateau contains mottled (speckled) white to yellowish clay to clay loam surface soil which quickly turns into rocky clay or solid limestone rock layers beneath the surface. Erosion has left most of the region with very shallow soils of less than 10 inches. Under this lies Edwards Limestone. You have probably seen examples of it all over the Hill Country. It is very porous and often has the appearance of a gray sponge. It is this limestone that hold the water found in the Edwards Aquifer.

The Blackland Prairie runs from just south of the Red River on the Texas-Oklahoma border through the Dallas-Fort Worth metropolitan area and into the San Antonio area and covers more than 19,400 square miles. The region is underlain by Upper Cretaceous marine chalks, limestone, and shale which give rise to the development of the characteristic black, heavy clay soils. Because of the soil and climate, this eco-region is ideally suited to crop agriculture. This has led to most of the Blackland Prairie ecosystem being converted to crop production or tame pasture grasses, leaving less than one percent of the native tallgrass remaining and making it the most endangered large ecosystem in North America.

To log this EarthCache, E-mail me the answers to the following question:
1. Describe the appearance of the exposed layer of earth at the given coordinates. Include the color and texture of the layer.
2. Does the exposed layer of substrate appear to have more characteristics in common with the Edwards Plateau or the Blackland Prairie?
3.What is the net gain in elevation between the parking lot and the provided coordinates of the exposed layer?
Parking is available at N 29 34.963 W 098 22.011. The park is open from dawn to dusk. Please remember to stay safe and obey the park rules. Remember, Keep it Clean! If you hauled it in then haul it back out (and take a little extra with you).