DRUMLINS OF CENTRAL WESTERN NEW YORK 423 



6 Long ridge drumlins. This includes two extreme varieties of 



form: (a) the long broad ridges or rolls or gentle swells which 

 are not generally recognized as belonging in the drumlin class, 

 . and commonly fail of representation on the contoured maps 

 [pi. t8"J; (b) the small, close-set, parallel ridges which lie as 

 minor moldings between the larger and conspicuous ridge 

 drumlins, or those which form the attenuated edge of a 

 drumlin belt [pi. 13]. 



7 Abrupt struck slopes [pi. 30, 35, 40]. 



8 Low or gentle struck slopes [pi. 22, 23]. 



9 Sharp crested hills with steep, or even concave, side slopes 



[pi. 29.] 



Many occasional or peculiar forms and characters might be noted 

 but they are not regarded as genetically important. 



The relationships of the several forms are not so definite or exclu- 

 sive as might be expected, though further study may discover new 

 facts. However, there are certain broad relations of distribution 

 and association which will be restated here. 



1 The drumlin area is practically restricted to the north-facing or 

 ice-opposing slope. 



2 The region of greatest development of drumlins is on the low 

 Ontario plain, which is nearly level. 



3 The greatest development lies over the greatest thickness of the 

 Salina shales, or where the drift is most clayey and adhesive. 



4 The predominant drumlin area lies where the ice flow was east 

 of south and at a high angle with the general southwesterly flow. 



5 The somewhat exclusive development of the long and low ridges 

 (6 a) is in the northwest corner of the State where the ice had only 

 the one direction (southwest) of flow, but where there was less 

 volume of clayey drift because less thickness of eroded shales. 



6 The individual drumlins are not placed in any orderly sequence 

 or regular disposition, but are irregularly spaced. 



7 Within the same belt of drumlins or what is regarded as a forma- 

 tional unit the south forms or those nearer the ice border are more 

 attenuated, while the north forms or those under the deeper ice are 

 broader. 



8 A belt of moraine drift lies in front of the attenuated border of 

 the drumlin belt. 



9 The greater hight of the drumlins, their steepness of slope and 



