Geomorphology and paleohydrology of Hurricane Crawl Cave, Sequoia National Park, California

Abstract

3 Abstract: Hurricane Crawl Cave in Sequoia and Kings Canyon National Parks, California, contains adjacent but varied passage morphologies including network and anastomotic mazes, large rooms, narrow canyons, prolific speleothems, and multiple levels that collec- tively are difficult to explain. We investigated the cave through cartography, geochronology, dye traces, modern discharge measurements, and paleodischarge estimates from scallop and cobble measurements. The cave has strong structural control along vertically oriented beds and subparallel fractures. 26 Al/ 10 Be burial dating of coarse clastic sediment suggests a minimum cave age of 1.4 Ma, and a time-averaged in-cave incision rate of 0.02 mm y �1 . Dye traces proved that an obvious surface stream is the source of the primary stream in the cave, but that other small streams rise from diffuse flow. Modern discharge measurements range from 0.042 to 0.002 m 3 s �1 . Paleodischarge and flow velocity values determined from scallops and cobbles vary more in relation to passage morphology than to passage elevation, a proxy for time. Paleodischarges were orders of magnitude larger than modern discharge. We attribute varied morphology and location of mazes to temporally and spatially variable sediment flux and stream discharges. Higher sediment loads and stream discharges promote the development of passages with anastomotic maze morphology. The morphology of Hurricane Crawl Cave differs from that Crystal Cave, which is in the same basin, primarily due to a comparatively lower sediment load.