MORAINIC COMPLEX 227 



lake of sufficient duration to permit the building of the moraine to the 

 level of the lake surface, but not to completely fill the lake and make a 

 plain. This belt of moraine is not very broad. 



North of this, and constituting the bulk of the valley moraine, is a 

 veritable morainic jumble. Below the level of the lateral moraine ter- 

 races, which were built at levels above the marginal lake, there is almost 

 no system in the moraine. The hummocks rise to various levels, and, 

 while there are numerous ridges extending out into the valley, there are 

 no distinct terminal loops. At several places, however, the morainic 

 hodge-podge is more massive and better defined than elsewhere, doubt- 

 less because the ice fronts stood there longest; but well defined moraine 

 occupies the entire area between these places of greater morainic devel- 

 opment. 



The irregular, indefinite form of the hummocks and ridges in the 

 latter belt, the exceptionally large proportion of stratified clay, and the 

 position of the deposit in a north-sloping valley, whose divide is higher 

 than the crests of the morainic hummocks, prove that this third type 

 of moraine is sublacustrine in origin. Its marked irregularity of struct- 

 ure and form, and the absence of definite terminal loops, indicate that 

 varied and, in part, unusual conditions were involved in its formation. 

 Among these conditions were standing water, rapidly moving water cur- 

 rents and eddies near the ice margin, direct dump of debris from the ice, 

 in wash of sand and gravel from the marginal and subglacial streams, 

 ice-shoving, the shove of grounding icebergs, and the melting out of 

 buried ice blocks, probably both stagnant blocks and stranded bergs. 

 Such a complex of conditions suffices to account for the jumble of mo- 

 raine in this section ; and the great length of the morainic area is readily 

 understood when we consider the fact that there is represented in this 

 valley moraine the effect of the horizontal oscillation of an ice lobe 

 during vertical recession of several hundred feet, as registered by the 

 hillside lateral moraines. 



Mode of Formation of the Moraines 



The field studies, of which the above is but a bare outline, prove con- 

 clusively that the moraines of the Watkins Glen quadrangle are prevail- 

 ingly, if not uniformly, of marginal and not submarginal origin. The 

 unequal development where marginal drainage was unequal, the presence 

 of marginal drainage channels in the lateral moraine bands, the distinct 

 moraine terraces and fronts with ice-contact faces, the steeply rising 

 ridges, both in the lateral moraines and the terminal moraine loops, and 

 the excessive kamey development of the moraine where marginal streams 

 descended into valleys, or where land streams flowed against the ice 



