THE MAMMOTH CAVE AND ITS INHABITANTS. 757 
masses of rocks fall in, which interrupt the passage below. one sapi 
however, exist when the strata are horizontal. Their is 
changed by joints or faults, into which the excavating ana eles 
found their w way. 
That these caves were formed prior to the postpliocene fauna is 
evident from the fact that they contain its remains. That they 
were not in existence prior to the drift is probable, from the fact 
that they contain no remains of life of any earlie er period so far as 
h in epoch. 
n extraordinary number of rapidly flowing waters must have 
operated over a great part of the Southern States, some of them 
at an elevation of fifteen hundred feet and over (perhaps two thou- 
sand) above the present level of the sea. A cave in the Gay 
Mountain, on the Kanawha river, which I explored for three miles, 
has at ware ae elevation. 
Th rritory experiencing such conditions was suitable for 
the occupation of such a fauna as the deposits contained in these 
caves reveal, is not probable. The material in which the bones 
occur in the south is an impure limestone, being mixed with and 
colored by the red soil which covers the gepi of the ground. It 
is rather soft but hardens on exposure to the 
The question then remains so far Se accel as to whether a 
pliocene mammalian fau That some important change too 
place is rendered ET by the fact, that nearly all the neotropi- 
cal types of the animals have been banished from our ee 4 
and the pren part of the species of all types have 
tinct. Two facts have come under my observation which tate 
a subsequent submergence. A seri ise of caves or portions of a 
single cave once existing on the southeast side of a range of low 
hills among the Alleghany mountains in Wythe Co., Virginia, was 
found to have been removed by asp fragments of the bot- 
tom deposit only remaining in fissures and concavi vities, separated 
by various intervals from each other. "Thio fragments yielded the 
remains of twenty species of postpliocene mammalia.* This de- 
nudation can be ascribed to local causes, following a subsidence 
T R nans In a cave examined in Tennessee the ossife- 
be accounted for on local grounds. The islands of the eastern 
part of the West Indies appear to have been separated by submer- 
gence of larger areas, at the close of the period during which they 
* See Proceed. Amer. Phil. Soc. 1869, 171. 
