ALLUVIAL DIVISION. 
109 
water is reached, which is a little above the level of the ocean. The wells gradually decrease 
in depth thence to the shore. On most of the farms in the interior, artificial means are resorted 
to, to procure a supply of water for cattle and other farm stock. A basin-shaped excavation 
is made in the soil, and puddled with clay, and into this the surface waters are conducted 
during rains. They are called watering holes, and are a striking feature of the farming 
economy of the island. 
6. Caves, Subterranean Streams, Natural Springs and Limestone Springs. 
Caves. 
Caves are not uncommon in the limestone regions of the First Geological District; but 
none, except those of Schoharie county, have been found so extensive as a few of those of 
Kentucky, Missouri, and some other States. All that I have examined seem to have been 
fissures in the limestone, the masses of which have been slightly shifted in position, perhaps, 
in some instances, by subterranean causes; but the cavities of the caves seem to have been 
principally formed by the solvent power of water, which gradually dissolved, and transported 
away the carbonate of lime to where it found an outlet as a spring upon the surface of the 
earth. Almost all limestone caves (and nearly all caves are found in limestone) contain 
either a stream or pool of water, connected with a spring on the surface; or if they are dry, 
a careful examination will generally demonstrate that they have been formed by running or 
standing water, which has dissolved away the rock. Limestone caves may, in fact, be con¬ 
sidered as the canals through which subterranean streams or rills either flow now, or have 
done so in times past. 
Tl'he caves of some parts of the world contain great numbers of the bones of various ani¬ 
mals ; others have been inhabited by man in a savage state, and show traces of his arts. 
Nothing of the kind has been discovered in any of the caves of the First Geological District, 
if we except the skeleton of a fox, which was discovered in Ball’s cave, Schoharie county, by 
Messrs. Gebhard and son and Mr. Bonny, which seemed to have fallen into the cave, and was 
unable to escape. The bat ( Vespertilio) assembles in immense numbers in our caves, to pass 
the winter. 
Some caves have a current of air passing out of them, and might perhaps be termed blow¬ 
ing caves, though not comparable with the Blowing cave of Virginia, described by Mr. Jeffer¬ 
son. This seems to be caused by the water falling in a cascade in a narrow space or fissure, 
carrying air along with it, which must necessarily find an outlet at some opening of the cave. 
The cave at the village of Clarksville in Bethlehem, Albany county, had a current of air pass¬ 
ing out of its mouth at the time I explored it, so strong as to make it difficult to enter it with 
-a lighted candle. This cave has water at a distance of one hundred or two hundred yards 
from its mouth; and although no water flows from its mouth, a large limestone spring issues 
near the creek, one hundred or two hundred yards from the cave, and is believed to be con¬ 
nected with the water of the cave. Small objects that would remain suspended in water, and 
that were left in the water of the cave, are stated to have come out from the spring. If this 
