<p>Structurally crinkled gyprock from the Permian of New Mexico, USA. (~7.9 centimeters across along the base)
</p><p>This is a sample of gyprock (rock gypsum), a finely crystalline-textured, chemical sedimentary rock dominated by the mineral gypsum (CaSO4·2H2O - hydrous calcium sulfate).  The light-colored layers are the gypsum.  The dark brown layers are calcite (CaCO3 - calcium carbonate).  Gyprock is an evaporite, which forms by the evaporation of water - usually seawater - and the precipitation of dissolved minerals.  All the layers here were originally flat, straight, and horizontal.  The fine-scale folding or crinkling formed during early Cenozoic structural deformation, not during an anhydrite-to-gypsum transformation (see Anderson &amp; Kirkland, 1987).
</p><p>Stratigraphy: Castile Formation, upper Upper Permian
</p><p>Locality: State Line outcrop, roadcut on either side of Rt. 180/Rt. 62, between Carlsbad Caverns National Park and Guadalupe Mountains National Park, immediately north of the Texas border, southern Eddy County, southeastern New Mexico, USA (32° 00' 34.2" North latitude, 104° 29' 55.0" West longitude)
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<hr><p>Reference cited:
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Anderson, R.Y. &amp; D.W. Kirkland.  1987.  Banded Castile evaporites, Delaware Basin, New Mexico.  Rocky Mountain Section of the Geological Society of America, Centennial Field Guide Volume 2: 455-458.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/48950516861/">Structurally crinkled gyprock (Castile Formation, Upper Permian; State Line outcrop, southern Eddy County, New Mexico, USA) 5</a>