Feb. 1901. Observations on Indiana Caves — Farrington. 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 



Op. cit., p. 287. 



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