310 F. Carney — Form of Outwash Drift. 



Proceeding southward from this area along the east slope of 

 Bluff Point, one traces a very sharp lateral moraine marking 

 the position of the valley tongue which occupied the Penn Yan 

 arm of the lake contemporaneously with the building up of 

 the outwash. This band of lateral moraine may be traced 

 without a break until it disappears beneath the surface of the 

 lake at a point a little south of Ogoyago. The counterpart of 

 this band of drift on the eastern wall of the Penn Yan branch 

 has not been traced continuously. It has been picked up, how- 

 ever, along the highway directly west of Warsaw, also to a 

 point northeast of Crosby, and continuously traced, where it 

 makes the angle around the divide west of Him rods, blending 

 then into marginal drift of the Seneca valley lobe. 



But the moraine which marks the position of the valley 

 dependency occupying the west branch of Keuka lake, at the 

 time the outwash was developing, attained only faint expression. 

 Its most pronounced development exists through the first mile 

 and one-half southwest of the drift in question. From that 

 point one cannot be certain of the outline of this valley depend- 

 ency. Its form, as suggested by drift flanking the west wall 

 of this branch of the lake, has not been investigated. 



The Normal Outwash Plain. 



Chamberlin cites* references to descriptions of the general 

 type of " glacio-fluvial aprons," variously named by geologists 

 from 1874-1893. But a precise summary of the terminology 

 of the deposits made by glacial waters, together with accurate 

 distinctions on genetic and topographic principles, f appeared 

 in 1902 in Salisbury's Glacial Geology of New Jersey, from 

 which we quote : " Where the subglacial streams did not occupy 

 subfflacial valleys, they did not always find valleys at hand 

 when they issued from the ice. Under such circumstances, 

 each heavily loaded stream coming out from beneath the ice 

 tended to develop a plain of stratified material (a sort of alluvial 

 fan), near its point of issue. Where several such streams came 

 out from beneath the ice near one another for a considerable 

 period of time, their several plains, or fans, were likely to 



become continuous by lateral growth Thus 



arose the tj r pe of stratified drift variously known as overwash 

 plains, outwash plains, morainic plains, and morainic aprons.";}: 



This definition of an outwash plain leaves no uncertainty : 

 genetically it results where there is a lack of alignment between 



* Glacial Phenomena of North America, in Geikie's " The Great Ice Age," 

 footnote p. 751, 1894. 



f Brief descriptions are also given in Chamberlin and Salisbuiy, Geology, 

 vol. i, p. 306 ; vol. iii, p. 372, 1906. 



% Geological Survey of New Jersey, vol. v, pp. 128-9, 1902. 



