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John R. Holsinger and David C. Culver 
Mountain and in Burkes Garden. The carbonate rocks are predomi- 
nantly limestones and dolomites of Cambrian and Ordovician age, 
although a limited exposure of Mississippian limestone crops out in the 
extreme northwestern part of the basin. The New River also drains sev- 
eral karst areas in adjacent West Virginia, and the cave fauna of these 
areas was discussed in some detail in a previous paper (Holsinger et al. 
1976). The regional cavernicolous fauna includes 29 cave-limited spe- 
cies; 26 are troglobites, and 10 are endemic to the basin (Table 8). 
5. Holston Basin . — That part of the Holston basin in the study 
area lies almost entirely in Virginia and extends only a few kilometers 
into Tennessee (Fig. 2). It is drained by three major tributaries of the 
Holston River and covers approximately 3690 km 2 . This faunal unit is 
defined by the Iron Mountains on the southeast, the drainage divide 
with the New River on the east, and Clinch Mountain and Moccasin 
Ridge on the north and northwest. Outside the study area, the basin 
continues southwestward through eastern Tennessee to the vicinity of 
Knoxville, where the Holston River joins the French Broad River to 
form the Tennessee River. The regional terrain varies from moderately 
rugged in areas drained by the North Fork to moderately rolling in the 
southern two-thirds of the basin drained by the Middle and South forks 
of the Holston River. The basin is bisected in part by Walker Mountain, 
which trends southwest and forms a prominent interfluve between the 
North Fork and Middle Fork. 
Although most of the exposed carbonates are limestones and dolomites 
of Cambrian and Ordovician age, limited outcrops of Silurian-Devonian 
and Mississippian limestones occur in parts of Scott and Washington 
counties. A total of 308 caves are recorded, and a number of them are 
large. However, much of the carbonate rock exposed in the southern 
part of the basin is dolomite and has limited the development of exten- 
sive caves. The regional cavernicolous fauna is composed of 19 cave- 
limited species; 18 are troglobites, and only three are endemic to the 
basin (Table 9). 
6. Clinch Basin . — Most of this basin lies within the study area and 
is drained by the Clinch River and its tributaries (Fig. 2). It is defined 
by the short drainage divide with New River on the northeast, the east- 
ern margin of the Appalachian Plateau and Powell Mountain on the 
north and west, and Clinch Mountain on the south except for a short 
stretch in Russell and Scott counties where Big Moccasin Creek flows 
north of Clinch Mountain before turning south to join the North Fork 
of the Holston River south of Gate City, Va. As defined in the present 
study, this faunal unit ends in Campbell County and in the vicinity of 
Norris Dam about 10 km south of where the Clinch River is joined by 
the Powell River; it covers approximately 4048 km 2 . Beyond the study 
area, however, the basin extends southwestward for approximately 60 
