By: yowich
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Uploaded: 2 Nov 2018
Last Updated: 13 May 2020
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Created by Youngwoo Cho 조영우 *** Please click on the tab to the right to switch on and off the annotations and markups. A road cut at Hoover Point of Backbone Ridge on E Farm to Market Rd 1431 near Kingsland, TX, USA, which is 675 ft or 206 m wide. The lower part of this roadcut which looks to be dark green layers is glauconitic Cambrian sandstones which are 505 to 570 million years old. The green color of this sandstone is attributed to the mineral glauconite, an iron-rich mineral commonly as fecal pellets of ocean organisms such as trilobites in a shallow marine environment. References Barnes, V. E., Bell, W. C., Clabaugh, S. E., Cloud, S. E., Jr., McGehee, R. V., Rodda, P. U., & Young, K. (1972). Geology of the Llano region and Austin area: field excursion. Austin: Bureau of Economic Geology, The University of Texas at Austin. Geocaching : Hoover Point - Green Coolness, https://www.geocaching.com/geocache/GC2A8BD_hoover-point-green-coolness?guid=f0894612-3bf2-43f7-a07a-496e4e7341db