4 
John R. Holsinger and David C. Culver 
Hunt 1967), the Interior Low Plateaus is sometimes referred to as 
“Appalachian” in the broad sense, because it is closely allied biologically 
and geologically with parts of the Appalachian Highlands. References in 
this paper to the “greater Appalachian region” include the Interior Low 
Plateaus. 
For all intents and purposes, the study area as defined above lies 
within the Appalachian Valley and Ridge province. Only its western 
periphery in southwestern Virginia and east Tennessee encroaches on 
the eastern margin of the Appalachian Plateau, where cavernous lime- 
stones crop out along the flanks of Cumberland and Stone mountains. 
The Appalachian Valley is underlain by folded and faulted bedrock that 
varies in geological age from Lower Cambrian to Upper Mississippian, 
about half of which is limestone and dolomite. The total number of 
caves recorded from the study area through 1980 was 2611, including 
2377 in Virginia and 234 in east Tennessee. 
Limestones in the Appalachian Valley and Ridge province are 
exposed on valley floors and along the sides of low ridges and are gen- 
erally restricted to long, linear strike belts. As a result, the principal 
orientation of most cave passages is along the regional strike (NE-SW), 
trending parallel to the valleys and ridges in which the caves occur. 
Strike-oriented belts of cavernous limestone are generally relatively nar- 
row and separated from each other by intervening parallel exposures of 
non-carbonate, clastic rocks such as sandstones, shales, and quartzites. 
Karst topography is generally common on most limestone terranes but 
is usually much more prominent in valleys floored by broad exposures 
of Middle Cambrian and Middle Ordovician limestones (Holsinger 
1975) (see Fig. 4). The overall drainage pattern is trellised, and, with the 
exception of a segment of the New River that flows north, most major 
streams flow roughly parallel to the strike (see Fig. 2). 
South and southwest of the study area, the cave region of the 
Appalachian Valley and Ridge extends through eastern Tennessee into 
northwestern Georgia and northeastern Alabama. North and west of the 
study area, it extends through eastern West Virginia, west-central 
Maryland and across south-central Pennsylvania. The Appalachian 
Plateau is capped with resistant, non-carbonate elastics of Pennsylvanian 
age, but in several places, especially on its eastern and western sides, 
cavernous limestones are exposed. On the eastern side significant 
exposures of limestones occur in eastern New York (Helderberg Plateau), 
southwestern Pennsylvania, western Maryland, parts of eastern West 
Virginia, southeastern Kentucky (Pine Mountain), east-central Tennessee 
(Grassy Cove, Lookout, and Sequatchie valleys), northwestern Georgia 
(Lookout Valley), and northeastern Alabama (Lookout, Sequatchie, 
and Wills valleys). Barr (1981a) appropriately termed some of these 
disjunct limestone areas “karst islands” to call attention to their 
