724 WALTER H. BUCHER 



trend. They are practically vertical. The strike of the one set 

 ranges from N 70 E to N 80 E with the majority lying between 

 N 75 E to N 78 E. The other set has a strike ranging from 

 N 20 W to N 10 E. Frequently joints of the two extremes, near 

 N 20 W and N 10 E, are present at the same locality. 



No detailed data are given for the large number of minor 

 joints of this region. Their trend seems to be highly variable, in 

 general and from point to point, and ranges through all points 

 of the compass. They are often curved and irregular, and as a 

 rule small. They generally show a large hade, ranging as high 

 as 60°. 



The remarkably uniform position of the two major joint 

 systems^ stands in strong contrast to the highly variable dip of 

 the limbs of the low anticlines and synclines formed by the rocks 

 of the region, as shown on the geological map.^ This contrast is 

 especially striking, as Miss Sheldon points out herself, where the 

 dip and strike of the rocks changes rapidly from point to point 

 along the pitching end of an anticline (for instance, the Shurger 

 Point anticline)^, while the position of the joint planes remains 

 unchanged. 



It is evident, therefore, that the formation of these joint sys- 

 tems was independent of the folding and followed it. 



Here, as on Crooked Creek, one system is quite constant in 

 its trend, while the other varies in such a way as to form angles 

 ranging from about 65° to 90° with it. We are, therefore, justified 

 in the assumption that they represent planes of shearing produced 

 by compression in a NE-SW direction under general conditions 

 of torsion. To test this interpretation, we turn to the geological 

 maps of Watkins Glen and Catatonk quadrangles. 



West of Ca3ruga Lake, along the axis of the Watkins anticline, 

 the contact of the Portage and Chemung formations is nearly 

 level, var3dng between 1,480 and 1,560 feet above sea-level for 

 a distance of over 18 miles. As it approaches the valley of Cayuga 

 Inlet, it rises above 1,600 feet. East of Ithaca, in the same general 



' See especially Figs. 6 and 7 of Miss Sheldon's paper. 

 ^ See Watkins Glen-Catatonk Folio, No. 169. 

 3 Loc. cit., p. 67. 



