Valleys 455 



is more open, and on the west side of Gannett hill leads southward over 

 a col at 1,680 feet into West hollow, to be described later. 



Bristol valley is drained by Mud creek or Ganargua river, which 

 escapes northward through the drumlin belt to the Clyde-Oswego drain- 

 age. The depth and narrowness of Bristol valley, the numerous " gulls " 

 or ravines which score its sides, many of which contain falls, the bold- 

 ness and increasing height of its walls, and the abrupt promontory at its 

 head, give it a wild and picturesque character which is unique among 

 the valleys of the region. 



High-level Valleys 



The plateau surface is broken by many high level valleys, each of 

 which presents its own peculiar problem. Among them three are worthy 

 of especial notice. 



Berby hollow lies 2 miles west of the upper part of Bristol valley and 

 parallel with it. It is 4 miles long and descends from 1,300 feet at the 

 south end to 1,100 feet at the north, where it is drained through the 

 gorge of Mill creek to the Honeoye. It differs from the larger valleys 

 in being sharply V-shaped. Its slopes rise steeply 600 to 900 feet. At 

 the south end it merges into and is continuous with the west fork of 

 Bristol valley. 



Frost hollow lies between the west fork of Bristol valley and Honeoye 

 valley. It is 3 miles long and half a mile wide. It is occupied in part 

 by a swamp at the 1,700 foot level, but more than half the area of its 

 floor is covered by a kame-moraine, which at the south end rises up 

 the slopes more than 100 feet. It once contained a small lake, but a 

 kame ridge across its middle now forms a divide, from which a stream 

 flows northward through Briggs gull to the Honeoye and another south- 

 ward into West hollow. 



West hollow is a continuation on the south of Frost hollow and the 

 west fork of Bristol valley. It is 1 mile wide and nearly 3 miles long. 

 Its surface is wholly occupied by a beautifully pitted outwash plain 

 from the moraines on the north, and slopes gently southward from the 

 1,500 to the 1,400 foot level. The southern margin drops abruptly to 

 the junction of the Honeoye and Canandaigua valleys (figure 1, plate 38). 

 The glacial drainage from West hollow combine with that from the 

 Honeoye glacial lake to form the great delta above Naples. 



Moraines 



classification 



The principal moraines of the region were described by Chamberlin 

 twenty years ago, and it will suffice to recall their location and to note 



