Tepee structure in Tansill Formation. Note the fact that if the upturned margins of the structure
were returned to a horizontal position, they could not be accomodated on a flat bedding plane;
this confirms the concept that these are expansion polygons. Light yellow layers are dolomitized
pisolitic and fenestral sediment; darker, gray layers are zones of sheet spar (aragonitic cement
crusts). Interstitial growth of aragonite (in marine or coastal spring settings) was the most
likely cause of sediment expansion and buckling. Outcrop at southwest end of parking lot at
Carlsbad Caverns visitor's center, Carlsbad Caverns National Park, Eddy Co., NM.

© Peter A. Scholle, 1999

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