346 E. B. MATHEWS SUBMERGED ^"DEEPS IN SUSQUEHANNA RIVER 



was sufficiently increased to cut long, narrow, spoon-profiled '^deeps/' 

 Their peculiarity lies in their extreme ratio of length to breadth, their 

 depth of cutting (at times below present sealevel), and their bottom pro- 

 files, which rise downstream to the general valley floor and do not persist 

 as canvons. 



