IN STRATA OF RECENT FORMATION. 105 
There is, however, no reason to consider these 
bones to be of high antiquity, as the rock in 
which they occur is of very recent formation, 
and is composed of agglutinated fragments of 
shells and corals which inhabit the adjacent 
water. Such kind of stone is frequently formed 
in a few years from sand-banks composed of 
similar materials, on the shores of tropical seas. 
Frequent discoveries have also been made of 
human bones, and rude works of art, in natural 
caverns, sometimes inclosed in stalactite, at 
other times in beds of earthy materials, which 
are interspersed with bones of extinct species of 
quadrupeds. These cases may likewise be ex- 
plained by the common practice of mankind in 
all ages, to bury their dead in such convenient 
repositories. The accidental circumstance that 
many caverns contained the bones of extinct 
species of other animals, dispersed through the 
same soil in which human bodies may, at any 
subsequent period have been buried, affords no 
proof of the time when these remains of men 
were introduced. 
Many of these caverns have been inhabited 
by savage tribes, who, for convenience of occu- 
pation, have repeatedly disturbed portions of soil 
in which their predecessors may have been 
buried. Such disturbances will explain the occa- 
sional admixture of fragments of human skele- 
tons, and the bones of modern quadrupeds, with 
