Subincrgoicc in the Narraga/isi'tt Bay. — Fuller. 311 
of the ice retreat in that vicinity. He found that the hights 
of the sand-plains indicated water standing at levels varying 
from twenty up to 150 feet above the present sea level. The 
level of the higher of these sand-plains, as for example' those 
of the Wickford stage, "is obviously determined by local 
topographical conditions."* In the case of the plains of the 
Greenwich Cove and Barrington stages, where there is evi- 
dence of the deposition of delta-like sand-plains "with the 
water as high as 50 feet above the present sea level, "'j- the 
topographical conditions afiford no explanation. 
The periods of high water during the deposition of these 
plains seem to have been followed, in each case, by a fall of 
50 feet or more at their completion. If ice remnants had re- 
mained in the passages of the lower bay, as Mr. Woodwortli 
suggested \ in his earlier paper on the retreat of the ice sheet 
in. the Narragansett bay region, the deposition might readily 
be conceived as taking place in the temporary lakes formed 
by such obstructions. In his later paper, however, he admits 
that "ice dams in Glacial Narragansett bay appear incapable 
of affording an explanation, "§ and concludes that the changes 
of level "are analogous to those of our large inland rivers, 
and come imder the head of flood changes," thus agreeing 
with the views set forth by Dana in regard to the upper limit 
of river border formations ; namely, as already indicated, that 
the hights of the waters had no direct relation to that of the 
ocean, but were determined by the enormity of the floods 
aided, possibly, as suggested by Woodworth, by the "gorg- 
ing" action of floating ice in the lower bay. 
The difficulty of* accounting for the pitch of the upper 
surface of the waters of the glacial bay under this hypothesis 
was appreciated by Mr. Woodworth, but the full extent of 
the requirements demanded by the postulated flood was evi- 
dently not realized. In the opinion of the writer, the ex- 
planation offered cannot be maintained. The causes so effi- 
cient when acting in the comparatively narrow valleys of our 
*Loc. cit, p. 154. 
tLoc. cit., p. 391. 
JLoc. cit., p. 168. 
§Loc. cit., p. 392. 
IIMan. Geol. 3rd Ed., p. 55i- 
