40 KINDLE 



is hole No. 3 on the Wilson property. On account of the attempt 

 which was made to save the Todd house, which stands partly over 

 this hole, by building a cement pillar foundation on the limestone 

 below the marl beds, the water was prevented by pumping from 

 rising to its normal level till recently. Since pumping has ceased 

 the water has risen to within 6 feet of the surface in this hole. 



The section exposed by the slumping of the soft beds into the cav- 

 ernous limestone shows at the top 1 to 4 feet of dark brownish earth 

 and clay. Below this is a bed which is mainly an ash-gray marl 

 containing great numbers of minute fresh water shells. Some beds 

 of yellow clay are inters tratified with the marl. These marly beds 

 have a thickness of from 20 to 50 feet. The well at the ice plant is 

 reported to have passed through about 12 feet of marl underlain by 

 14 feet of clay. The shaft on the Yost property is reported to have 

 penetrated only clay. Previous to caving the soft marl appears to 

 have been prevented from slumping into the limestone channel by 

 a tightly packed tough limestone clay. A small collection of shells 

 was obtained from the marl beds by the writer. These have been 

 determined by Dr. Paul Bartsch who has furnished the following 

 list of the species represented: 



Bythinella nickliniana Lea 



Planorbis bicorinatus Say 



Planorbis parvus Say 



Pisidium sp.? 

 These all represent living species which are common to the streams 

 and ponds of the southeastern states, thus indicating the post- 

 Plistocene or recent age of the beds. 



A question of primary geologic as well as practical interest in 

 connection with the caving is the direction followed under the town 

 by the underground stream or cavern which is responsible for the 

 caving. A brief examination of the bed rock stratigraphy in the 

 vicinity of the caved area suggests that the underground course 

 of this stream or cavern may be determined from stratigraphic 

 data within the probable limits of future caving. The basis of this 

 deduction will appear from a brief statement of the general factors 

 controlling underground erosion in limestones and the particular 

 factors which are chiefly effective in this case. It is a familiar fact 

 that "the primary cause of motion in underground waters is gravi- 



