The Ice-Sheet in Nnvi-agansett Bay. — Woodirorfh . 151 
its bordering Narragansett bay. The studies liere presented 
will appear in a less detailed account, and without the theo- 
retical considerations here given, in a forthcoming atlas folio 
descriptive of the Pleistocene deposits of the Narragansett 
Bay atlas sheet, the mapping of which was done under the 
•direction of Prof. N. S. Shaler. It should be stated that while 
that geologist is in full accord with the author as to the na- 
ture of the deposits here discussed, the author alone is respon- 
sible for the views which are here set forth regarding the 
circumstances of the origin of the glacial sand-plains and 
their attendant deposits. 
The passenger by rail from Boston or Providence southward 
along the Shore Line cannot fail to notice a certain repetition 
in the landscapes observable from the car window. Going 
from north to south the views may be summarized as follows: 
1. Lowland or valle}'^, from one to five miles wide, either 
boulder-strewn and marked by mounds of gravel and an occa- 
sional esker or occupied b}^ sluggish streams and swamps, and 
terminated rather abruptly on the south by the next. 
2. A terrace or steep bank facing northerly, often hum- 
mocky or kame-like. The train plunges at once into a deep 
gravel or sand cut. From the edge of the terrace the sky- 
line of the cut gradually sinks to the southward and in a few 
minutes a view may be had out over the surface of the sand- 
plain. At a distance varying from a quarter of a mile to a 
mile this plain terminates in more or less w^ell defined lobate 
spurs resting on ground of a variable nature, often boulder- 
strewn, but sinking usually at a short distance into a swamp, 
and in general repeating all the features described under the 
first heading. 
An analysis of these sand-plains shows that they character- 
istically have the steep northern aspect with cusps or kames 
indicating the deposition of the materials along and against 
the margin of the ice-sheet. Along the line of extension in- 
dicated by this contact with a now-vanished ice-wall, there 
are usually found other sand-plains, the accumulations thus 
marked forming belts from a quarter to half a mile in width, 
roughly concentric to the outer moraines along the southern 
coast between point Judith and cape Cod. 
