Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 67 Number 2: 92-102 - August 2005

A publication of the National Speleological Society

Geomorphic history of Crystal Cave, Southern Sierra Nevada, California
Joel D. Despain and Greg M. Stock

Abstract

Cave development in mountainous regions is influenced by a number of factors, including steep catchments, highly variable allogenic recharge, large sediment fluxes, and rapid rates of canyon downcutting. Caves can help to quantify this latter process, provided their ages are determined. Here we investigate the history of 4.8 km long Crystal Cave, a complex, multiple level cave in the Sierra Nevada, through detailed geomorphic and geochronologic investigations. Crystal Cave is composed of six major levels spanning 64 m in elevation. The levels are comprised of large, low gradient conduit tubes, and are connected by numerous narrow, steeply descending canyon passages. Passages in the upstream end of the cave are significantly modified by collapse, while in the downstream section they are intact with an anastomotic maze overprinting. Dye tracing confirms that the cave stream originates from partial sinking of Yucca Creek to the north. Passage gradients, wall scallops, and sediment imbrication indicate that groundwater flowed consistently southeast through time, forming cave levels as bedrock incision of Cascade Creek lowered local base level. Although modern cave stream discharges are restricted to ~0.03 m³ s-1, likely due to passage collapse near the sink point ca. 0.5 Ma, bedrock scallops and coarse clastic sediment in upper levels indicate paleodischarges as much as three orders of magnitude greater prior to that time. Infrequent high discharge flood events played an important role in passage development and sediment transport. Cosmogenic 26Al/10Be burial dating of sediment suggest that the majority of Crystal Cave formed rapidly between ca. 1.2 and 0.5 Ma; rates of cave development approach theoretical maximums, presumably due to a combination of allogenic recharge highly undersaturated with respect to calcite, and physical erosion by transported sediment.

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