EXAMPLES OF JOINT-CONTROLLED DRAINAGE 



3 6 9 



hand, to glacial erosion. At the St. Louis meeting of the Geological 

 Society of America, held in December, 1903, the writer pointed out 

 that, irrespective of which of the two agents had performed the major 

 part of the work of excavating the valleys, the cause of the striking 

 rectilinear extension of the valleys and their peculiar arrangement 

 necessarily called for a control of whichever of the agents accom- 

 plished the work. From Professor Tarr, who was present at the 



Fig. 5. — Vertical rectangular joint set on east shore of Cayuga Lake, Ithaca, 

 N. Y. (Photograph furnished by Professor R. S. Tarr.) 



meeting, it was learned that Mr. Charles G. Brown, editor of the 

 Holstein-Frisien World, had undertaken the measurement of joint 

 directions within the Cayuga Lake Basin as a thesis for graduation 

 when a student at Cornell University. Mr. Brown has very kindly 

 placed his results at the writer's disposal, and from a somewhat 

 extensive survey of literature the writer is convinced that they con- 

 stitute not only the most extensive, but also the most consistent, 

 series of observations of the kind that has yet been made. This is 

 probably in part to be explained by the perfection of the joint system 

 within the district studied. 



