Synsedimentary fracture (neptunian dike) in the Capitan reef showing parallel
on opposite walls of fracture seen in an acid-etched outcrop. Latest stage filling in center of
fracture is clastic terrigenous silt piped down from an overlying surface of transport. Fractures
trend parallel to reef front and extend essentially vertically down through the reef and into
upper fore-reef talus facies. These are the cause of the "spurs" seen in photographs of upper
slope and reef outcrops. Outcrop at the south spur of the mouth of Walnut Canyon, just
outside boundary of Carlsbad Caverns National Park, Eddy Co., NM.
© Peter A. Scholle, 1999