MERWIN: SHORE-LINES. 315 
When the ice-front had receded so far as to free this valley of ice, 
it, at the same time, left free the valley of Hollow Brook, which comes 
into this valley from the east. There is a conspicuous terraced delta 
at the mouth of the Hollow Brook valley. The top of the highest 
terrace (665 ft.) is about 20 feet too high for it to be considered con- 
temporaneous with the highest level of the Bristol delta, allowance 
being made for tilting according to the evidence given by certain 
shore-line features on the New York side of Lake Champlain. Yet 
these deltas in Vermont are so much better defined, and so much 
further north of the Coveville outlets of Lake Vermont, that they 
probably more accurately define the slope of the Upper Coveville 
stage than do the shore-line features in New York. Furthermore, 
if the southward tilting of the shore-lines is due to unloading of the 
land at the north as the ice-sheet melted, then the first formed shore- 
lines should slope more than those formed later, provided, of course, 
that uplift took place at intervals during the unloading, as well as at 
intervals since. 
The Hollow Brook delta is much too large to have been built during 
the life of Lake Vermont by any stream or ice discharge from the 
basin which the brook now drains. An explanation of the existence 
of the delta is found 3 miles up the valley at a divide between Hollow 
Brook and a stream which flows into the Winooski River. In the 
water-laid deposits which cover the surface at this divide there is : 
stream-made trench about 50 feet deep. The floor of the trench is 
only a few feet higher than the upper level of the delta. This trench 
is evidently the abandoned outlet of a lake which occupied the lower 
part of the Winooski basin. As a further confirmation of this idea, 
I found banded clays dipping west in the valley east of the divide. 
Wave lines marked by rounded cobbles and patches of gravel occur 
at heights of 240 and 265 feet above the sea, near the northern cross- 
road on the low limestone ridge leading southwestward from Ver- 
gennes.! In the clayey walls of a drainage ditch one fourth of a mile 
west of the railroad station at Vergennes at an altitude of 180 feet, I 
collected ten valves of Macoma groenlandica. These marine shells 
had been transported, I believe, a little way off shore from where 
they had been living in the shallow water at the base of a limestone 
hillock. The shells occur about 50 feet below the upper marine limit. 
About 4 miles east of Vergennes, Little Otter Creek flows out of a 
basin about 2 square miles in area through a gap in the western rim of 
1 This ridge was mistaken by Baldwin (’94, p. 172) for an esker. 
