52 
Frank Carney 
But the moraine which marks the position of the valley depend- 
ency 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 dependency. 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 distinc- 
tions on genetic and topographic principles,^ appeared in 1902 in 
Salisbury’s Glacial Geology of New Jersey, from which we quote: 
Where the sub-glacial streams did not occupy sub-glacial valleys, 
they did not always find valleys at hand when they issued from the 
ice. Under such circumstances, each heavily loaded stream com- 
ing 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 an- 
other for a considerable period of time, their several plains, or 
fans, were likely to become continuous by lateral growth * * * 
Thus arose the type of stratified drift variously known as over- 
wash plains, outwash plains, morainic plains and morainic aprons.”® 
This definition of an outwash plain leaves no uncertainty: gen- 
etically it results where there is a lack of alignment between sub- 
glacial valleys and sub-glacial loaded streams: topographically 
these streams should flow out upon a plain where their individual 
fans may coalesce. It is also evident, as Salisbury states elsewhere, 
^ Glacial Phenomena of North America, in Geikie’s The Great Ice Age^ foot- 
note p. 751, 1894. 
^Brief descriptions are also given in Chamberlin and Salisbury, Geology, voL i, 
p. 306; voL iii, p. 372, 1906. 
® Geological Survey of New Jersey, vol. v, pp. 1 28-129, 1902. 
