Pleistocene Geology of Moravia Quadrangle 
401 
of ice extending eastward into the tributary valley became stag- 
nant here. Before the mass of ice had thinned down to a level 
where ‘‘ablation moraine might gather, thus protecting it from 
speedy decay, drainage lines were developed beneath it, particularly 
from the point where marginal or superglacial streams gave a 
head to the water. Consequently this esker resulted from the 
escape of water confined between the ice and the high ground to 
the north and east. The eastward extending tongue of ice here 
formed a barrier which in connection with the ice in the Fall Creek 
valley adjacent held up the drainage gathering from the north as 
well as that coming from the decaying ice. The only outlet for 
these waters was around the end of the ice tongue, a course which 
the drainage for some time did take, but as the ice became more 
and more stagnant the subglacial course was developed. Fur- 
thermore, the material of this esker is prevailingly fine, indicating 
that the chief source of supply was found in the kames where it 
originates. 
While No. 4 is plainly also the result of a gravitative direction 
given to drainage, the further point of variation in texture indi- 
cates different conditions than obtain in No. 7. Here we have no 
feeding kame area; we have a strong suggestion of coarse till-like 
material in the esker. Throughout its length, so far as may be 
1 mapped with certainty, there is a slight fall, which may account 
partly for the absence of washed material. Terminally the esker 
is without characteristic features. 
By consulting the topographic map we note that the topography 
in the vicinity of esker No. 9 favored the development of a re- 
entrant angle of ice-free surface. Thus the ice here formed a 
saddle; in the sag between it and the rising land south Water accu- 
mulated. Judging from the present contours, and granting the 
most favorable condition of this interpretation, such a body of 
water had slight areal extent and apparently during most of its 
period did not have a depth of more than twenty feet; but as the 
! ice decayed, it became somewhat larger and deeper. If a stagnant 
' condition of the ice existed for but a short time we may under- 
I stand how this water found a sub-ice outlet, associated probably 
, with a subglacial stream already flowing southward along the 
east wall of the valley towards Locke. The slight development 
of this esker indicates the short duration of the stream. 
^®Tarr: Zeitschrift fiir Gletscherkunde, band iii (1908), pp. 85-88. 
