4 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
(Bateman 1988; Stock and Moore 2003). The ages of the karst caves are not well known, but dat¬ 
ing of cave deposits indicates that caves of the southern Sierra began forming in the late Pliocene 
and Quaternary, ~5 Ma to the present (Stock and Anderson 2002). In the Mother Lode region 
(northern Sierra Nevada) deposits of Pliocene volcanic rocks (5.3 to 2.6 Ma) fill older karst caves 
and similar features (Bruce Rogers, pers. comm.). Cave sediments along the Stanislaus River in the 
central Mother Lode were dated to about 1.63 Ma by cosmogenic 26 Al/ 10 Be burial dating (Stock, 
Anderson, and Finkel 2004). Many of the Sierran caves mark former river levels etched into the 
bedrock walls of deep river canyons that were uplifted about 3 Ma. Coarse sediments in Clough 
Cave, southern Sierra Nevada, are 1.03 +/- 0.13 Ma per cosmogenic 26 Al/ 10 Be burial dating, but 
the cave could be much older (Stock et al. 2005). 
The Sierra Nevada was repeatedly glaciated during the Pleistocene Epoch between 2 Ma to 10 
ka (thousand years ago). During the glacial maximum about 22,000-18,000 ka, the Sierra had an 
icecap about 430 by 30-50 km. During the most recent glaciation valley glaciers descended to alti¬ 
tudes of 900 to 1,200 m. More than 15 glaciations may have occurred (Stock and Moore 2003). 
These glaciations could have caused repeated isolations, colonizations, and extinctions of cave 
fauna. 
As a result of the great relief among caves in the southern Sierra Nevada (500-3,350 m above 
sea level), archipelagoes of caves and karst occur in a variety of different ecological zones, includ¬ 
ing grass and oak woodlands, pine forests, steep river canyons, and alpine areas. Cave temperatures 
range from 0 to 18°C. Few areas in North America display such ecological diversity in cave and 
karst areas over such short distances (Stock and Moore 2003). 
Lava flows in Siskiyou County range in age from 200 Ma, to 4-3 Ma, and as recent as 
114-12.3 ka at Lava Beds National Monument. Subway Cave, in the Hat Creek Lava Flow of Shas¬ 
ta County, is less than 2,000 years old. In many lava flows there has been ample time for animals 
to become isolated in the lava flow crevices and tubes and evolve subterranean adaptations. 
California’s Cave Regions 
Geology and physiography combine to divide the caves into a number of isolated regions and 
karst areas. The 12 regions in this paper (Fig. 1) correspond in part to commonly used biological 
regions. The Central Valley (Sacramento Valley and San Joaquin Valleys) has very few caves. In 
this paper the three coastal regions are treated in tabulations as one region, Coast Ranges. Our eight 
primary cave regions are defined to summarize cave geology and cave biogeography, providing a 
framework for broader summaries and biogeographic analyses. The descriptions of these regions, 
subregions, and cave areas that follow are derived from Halliday (1962), Bateman (1988), Stock 
and Moore (2003), Bruce Rogers (pers. comm.), and our own observations. Our relational database 
and geographic information system (see Methods) created with this effort will facilitate future bio¬ 
geographic research, including smaller areas with distinctive faunas. 
More than 4,600 caves are currently known in California (Bruce Rogers, pers. comm.). We 
have general locational data for about 2,776 sites in many rock types; this includes 1,322 caves, 
pits, rockshelters, sinkholes, crevices and talus; 451 lava and ash caves; 405 littoral (sea) caves; 
260 groundwater sites (including 38 sampled springs, 44 streams and lakes, 49 other hyporheic 
habitats below streams, and 6 wells); and 223 mines. Table 1 provides details on regions, types of 
sites, and numbers of sites that were biologically sampled. 
Cave Region 1 — Klamath Mountains 
This region, similar to the conventional Sierra-Klamath region, comprises western Siskiyou, 
