234 E. T. Long — Minor Faulting 



have been preserved on the fault plane. It is almost 

 impossible to get data for the third dimension and impres- 

 sions are correspondingly vague. 



Quite the reverse is the case in the Encrinal layer. In 

 the locality of Ludlowville and on the opposite shore, 

 faulting is more frequent than farther north, and the 

 Encrinal bed here consists of nearly two feet of coarsely 

 comminuted crinoid fragments containing well-preserved 

 fossils of good size. It is hard and compact, though 



Fig. 3. — Striated columnal structure due to movement under compression 

 along fault planes in the Encrinal layer between Crowbar and Willow Cr., 

 west shore Cayuga Lake. 



coarsely crystalline, forming ledges or waterfalls as the 

 conditions determine; a typical "competent" bed, in 

 which the faults conform to the laws of shearing under 

 horizontal compression, where the direction of least 

 resistance is both upward and downward into the com- 

 aratively mobile shale. The fault planes dip both to 

 the north and the south at angles varying from 20°-30°, 

 and on both sides of the plane show striated columnar 

 structure produced by movement under pressure (see 

 iig. 3). The most numerous collection of these faults is 

 found on the west shore of the lake midway between 

 Crowbar and Willow Cr. and in a second strip of Encrinal 



