EXAMPLES OF JOINT-CONTROLLED DRAINAGE 



367 



II. THE FINGER LAKES DISTRICT OF WESTERN NEW YORK 



The Finger Lakes district has long been a classical one for the 

 perfection of its joint planes, a cut from the locality having been 

 used by Dana in his Manual of Geology as the type illustration of 



Fig. 3. — Canyon formed along a joint plane. Enfield Gorge near Ithaca, N. Y. 

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



joint structures. Later photographs, which the writer owes to the 

 courtesy of Professor Tarr, of Cornell University, show beyond 

 question that the joint system has exercised an important control 



