Differential Cave Erosion
December 12, 2004
A cave is typically formed when limestone is dissolved by the flow of weakly acidic water, then re-deposited as calcium carbonate stalactites and stalagmites. But what caused the unusual formations seen in this photo? In this cave (Peppersauce Cave, in southern Arizona), horizontal bedding planes of harder iron-rich material were formed within the sedimentary limestone. Later, after the layers were uplifted and tilted, the cave was formed. In a process called differential erosion, the surrounding limestone dissolved faster than the harder material, leaving these layers exposed as tilted parallel plates.