Officer's Cave, a Pseudokarst Feature in Altered Tuff and Volcanic Ash of the John Day Formation in Eastern Oregon

Abstract

Officer9s Cave is the uppermost of four rapidly eroding cave levels constituting a cavern complex about 700 feet long developed chiefly in clay and silt. Its outer room is 35 feet by 43.5 feet by 100 feet and slopes about 45° east into the western end of a narrow linear hill called Officer9s Cave Ridge. Dry valleys, blind valleys, hanging valleys, sinkholes, pipes, caves, and natural bridges are abundant. These, together with subterranean drainage, give the area a karstlike development. For such terrains the term “pseudokarst” is applied. These pseudokarsts are the product of piping and are fairly widespread over the world9s drylands.