MOUNT GREYLOCK. 



143 



On a polished surface they can easily be traced. (See. Fig. 39.) On the 

 north side of the ridge, south of the Hopper, (locality 899) the stratifi- 

 cation foliation is indicated by white calcite meandering through the 

 gray limestone. At a small cave about two-thirds of a mile northeast of 

 the Lanesboro Iron Company's ore bed (locality 998) the relation of cleav- 

 age to stratification in limestone is also clearly seen. That the plane folia- 

 tion is cleavage foliation is rendered highly probable from the usual char- 

 acter and origin of such foliation'. There may be cases, however, where it 

 would be difficult to decide whether the plications in limestone are due to 

 "false bedding" or to original stratification. 



From all this it appears that cleavage phenomena in the Greylock area 

 affect both schist and limestone. 



CASE IV. 



In some loose pieces of limestone found on Quarry hill, New Ashford, 



Fir,. 40.— Loose piece of limestone* from Quarry hill, New Ashford, showing on the weathered surface lamina; of 

 micaceous matter in both cleavage and stratification planes The nearly horizontal lamina' represent the stratification 

 foliation. From a photograph. 



both cleavage and stratification foliation are indicated by laminae of mica- 



1 Cleavage foliation may be subsequently bent, but this rarely occurs. See Ch. Darwin, loc. cit., 

 also J. 15. Jukes: Student's Manual of Geology, edited by Archibald Geikie. 3d ed., Edinburg, 1872, 

 p. 224, 225. Dr. H. Retiscli in his Geology of the Islands of Bommelo and Karrno, etc., already cited, 

 describes on p. 196, Fig. 2, and p. 40S, an interesting specimen from Foien, an islet at the mouth of the 

 llardangerfjord in Norway. The specimen figured shows both the original stratification foliation 

 I plicated i and the ensuing cleavage foliation (slip cleavage), and also the secondary plication of both 

 of these foliations, all on a small scale. One or two Greylock specimens show a slight flexure of the. 

 cleavage foliation. Plicated cleavage in the Taconic range at West Rutland. Vt., is described in the 

 author's report on the Rensselaer Grit Plateau in the Thirteenth Annual Report of the Director of 

 the U. S. Geological Survey, pp. 291-340. See also A. Baltzer, op. cit. (p. 152), pi. xin, tig. 11. 



