EXAMPLES OF JOINT-CONTROLLED DRAINAGE 



373 



the Seneca line, which is directed about N. io° W., and which for 

 a distance of nearly 60 miles is outlined in part by Seneca Lake 

 itself, to the south by an open valley which extends as far as Elmira, 

 and to the north by a reach of Canandaigua Outlet. Three linea- 

 ments, nearly parallel, are directed in a nearly perpendicular direction 

 to the Seneca line, and may be designated respectively as the Seneca 

 Falls line, the Penn Yan line, and the Watkins Glen line. For a 

 portion of their extent these lines correspond to the boundaries of 

 formations, and the fact that they are fall lines is thus in part explained. 

 Their alignment, however, is no less significant, since the joint planes 

 have so largely determined the areal limitation of the formations. 

 The line of Owasco Lake is directed N. 20 W., and may be followed 

 in the drainage for a distance of about 40 miles. The line of Skane- 

 ateles Lake and Tioughnioga River together make a prominent 

 lineament directed N. 30 W., and followed for a distance of about 

 40 miles. Upper Cayuga Lake and its extension in drainage lines 

 to the northwestward and southeastward mark out a lineament 

 whose direction is N. 37 W., and which may be followed for some 

 70 miles. Less striking lineaments are directed along Canandaigua 

 Lake (N. 18 E.), Cayuga Outlet (N. 15 E.), and along Flint and 

 Twelve Mile Creeks (N. 22 E.). 



Comparing, now, these lineaments with the joints observed by 

 Mr. Brown, we have: 



The directions of the Seneca, Owasco, Upper Cayuga, and Seneca 

 Falls lines are respectively those of the second and first in relative 

 numerical importance among the joints observed in the district, as 



