392 Frank Carney 
The ridges of the first area referred to appear to be construc- 
tional in origin; their direction marks the lateral margin of the 
declining Owasco lobe. This genesis seems less applicable to 
the ridges of the second locality; here conditions favored stream 
erosion which may have been a factor. The Benson Corners 
area apparently represents initially the drift that accumulated 
in the reentrant angles where the ice-margin had locally assumed 
a serrate outline; erosion has later altered these deposits, flatten- 
ing them in the direction of the slope, i. e., to the northwest. 
Valley Trains and Outwash Plains. 
Both these forms of drift have to do quite as much with topo- 
graphical relationships as with the positions of ice halts. In a 
longitudinal valley having so constant a slope to the north that a 
continuous ice-dammed lake is held up as the ice tongue recedes, 
we will not find illustrations of the typical valley train. This 
form of drift develops best in valleys having a slope away from 
the ice-front; but an initial iceWard slope of the valley may be 
reversed by the gradual filling of the lake from the ice-contact end. 
With this topographic condition, then each loop of drift may con- 
nect southward with a valley train. In any event there is bound 
to be some distribution of drift away from the loop, which marks 
the position of the ice, even when a static body of water rests 
against the loop being formed. In this case the plain of more or 
less modified drift will be shorter and evidently also steeper in 
slope since it will represent the deposition of material held in sus- 
pension by the water; and with a continuance of these deposits 
the grade in this part of the valley would at length be changed, 
and outwash material be built up normally. A section of deposits 
made under these conditions would show clay at the bottom grad- 
ing upward into gravel. 
It is observed that Fall Creek valley from lake Como southward 
offers the only area for the normal development of valley trains. 
Since the development attained by a valley train is intimately 
connected with the development of the moraine loop with which 
it is associated, it follows that we have the most pronounced 
trains only where the loops are conspicuous. In Fall Creek 
valley the particular halts of the ice, with one exception, appear 
to have been brief. The Como halt is characterized by a marked 
