Geologic features are often a story of sedimentation over long periods of time, followed by erosion (sometimes over equally long periods of time, sometimes in a matter of hours or days). The Caprock Escarpment, marking the difference between the high plains of the Llano Estacado and the Low Rolling (Red Bed) Plains to the east, is especially noticeable just south of Post, TX, to the west of U.S. Highway 84. This unique geology also formed numerous oil deposits in the area. Just as erosion has changed the topography, the supply of oil has eroded through production, to the point that alternative means such as wind power have become increasingly important as current and future sources of energy. This earthcache is designed to show the changes due to erosion, provide a glimpse of renewable energy sources, and make a connection between the wind’s power to generate electricity and the power for erosion. The following stops and tasks can be completed in 30 minutes, measured from the time of leaving U.S. Highway 84 to the return to the same location. Here are the two stops and four requirements to complete the Earthcache.
1. Exit U.S. Highway 84 about 19 miles southeast of Post and proceed south on Farm-to-Market road (FM) 1269. Drive 2.5 miles to reach the waypoint. At the waypoint, count the number of clearly distinct (i.e., differences in color) rock layers in the cliffs. Task #1: Email me the number of layers.
Waypoint: N 32° 57.765 W 101° 08.909
2. Proceed 0.8 miles south along FM1269, up the Caprock Escarpment and onto the plains above. Quite a difference of conditions in just one mile! At the waypoint below you have three tasks to complete.
Waypoint: N 32° 57.010 W 101° 08.872
Task #2: Water erosion is the main player in the formation of the cliffs, but wind erosion is also important. It’s obvious here that the wind exerts a large force for erosion – you can actually see it turning the wind turbines. Even though the wind turbines do not measure the total potential force of wind erosion, a simple calculation can provide some perspective of the power involved. Email me the answer to the following question: How many wind turbines do you see east of FM1269? Remember, FM1269 is a north-south road, and you have a GPSr, so figuring out which side is east should be easy.
Task #3: The wind farm is estimated to power 30,000 average Texas homes. Each turbine powers roughly 187 homes. The measurement phase of this earthcache is to multiply the number of turbines from Task 2 by 187 to see how many homes are powered by the turbines on the east side of FM1269. For example: (50 turbines X 187 homes/turbine) = 9350 homes. Email me the estimated number of homes. Now consider that the power collected by the turbines is only a fraction of the wind blowing on/over this plateau.
Task #4: There was a large sign at the site indicating the number of days without a recordable injury. This has blown down. While not a requirement for logging the cache, pictures of your group or GPSr with the turbines are appreciated.
As usual, do not post answers to the questions or a picture of the rock layers from Task #1. Any posts containing those items will be deleted.
Additional information can be found in Roadside Geology of Texas by Darwin Spearing, Copyright 1991, Mountain Press, ISBN 0-87842-265-X