Fes. 1g0r. OBSERVATIONS ON INDIANA CAVES—F ARRINGTON. 257 
STREAM Deposit.—Gradual diminution in rate of flow is well 
shown in the deposit left by a stream tributary to the main stream to 
be seen at the point called the ‘‘Sand Pit”’ between the ‘ Rock of 
Gibraltar” and “Fortress Monroe.” The stream had a course 
nearly at right angles to that flowing through the main cave, although 
its course, as its channel is filled nearly to the roof, can not be fol- 
lowed backward except by digging. Where this tributary emptied 
into the main stream it formed a delta deposit about eight feet in 
depth. The main stream in cutting downward has cut through this 
delta so as to expose a complete section. The deposit is well strati- 
fied. There are slight variations in the coarseness of adjacent strata 
throughout the deposit, but the most striking feature is the obvious 
gradation from coarse pebbles at the bottom to fine alluvium at the 
top. The pebbles at the bottom are well rounded sandstone pebbles 
having about the size of English walnuts. Only a stream of con- 
siderable swiftness and volume could have transported them. From 
such a velocity of current the stream diminished until it bore only the 
finest alluvium in its latest stages. What could have led to such a 
diminution in its rate of flow is not apparent, but it is evident that 
waters flowing through limestone are liable at any time and to any 
extent to be drawn off in new directions by the opening of new con- 
duits. 
ABUNDANCE OF STALAGMITES.—A remarkable feature of the por- 
tions of the cave known as ‘‘Cave Hill Cemetery” and the ‘‘ Prison 
Cell” is the relative abundance of stalagmites. Many of the stalag- 
mites have no corresponding stalactites at all. There can be little 
doubt that the principles enunciated by Senft* provide adequate ex- 
planation of the origin of such results. Senft showed that when 
the flow of water through a crevice was too rapid, either on account 
of the verticality of the crevice or the abundance of the water supply, 
to allow of evaporation and consequent deposition sufficient to form 
a stalactite, a stalagmite might yet be built up because of the greater 
opportunity for evaporation given for water falling upon the cave 
floor. He supported this conclusion by calling attention to the fact 
that stalagmitic icicles form during the hours of the day when melting 
is most speedy. These suggestions seem to furnish sufficient 
explanation for the facts referred to. 
ORIGIN OF PECULIAR FoRMS OF STALAGMITES.—The form of many of 
the stalagmites is remarkable and, so far as I know, peculiar to this 
Of. cit., p. 287. 
