Variations in Evaporite Karst in the Holbrook Basin, Arizona

Abstract

impoundments for effluent discharge from a nearby pulp mill. Four major drainage events occurred within these playa reservoirs during the past 45 years, collectively losing more than 1.23 x10 7 m 3 (10,000 acre-feet) of water and playa sediment. Drainage occurs through piping into bedrock joints in Triassic Moenkopi Formation (sandstone) in the bottom and along the margins of these playas. Effluent discharge has been discontinued into these playas, although recurring precipitation can fill the basins. Local ranchers have continued to report periodic sinkholes forming when the valley floor flooded. These karst features are among the lesser known geomorphic curiosities in Arizona, but surely one of the most spectacular displays of evaporite karst in the United