Review of Recent Geological Literature. 47 
Mr. Bell concludes that the clay and its shells were both sup- 
plied from an ice-sheet which eroded preglacial marine beds 
from the basin of Loch Ness (now about ">() feet above the sea 
and 774 feet deep), depositing the (lava strata in a glacial 
lakelet held in a nook of the Nairn valley by a harrier of ice 
which later advanced again, forming the upper till. 
Mr. Bell's view seems to he almost the same as that held by 
Prof. G. F. Wright and Mr. Prentiss Baldwin to account for 
their discovery of marine shells in the upper part of an equally 
thick deposit of modified drift, overlain by till, about 500 feet 
above the sea, at Ketley, near Wellington in Shropshire, Eng- 
land (Am. Journal of Science, III. vol. xi.in. pp. 1-8, Jan.. 
1892). It also well accords with the occurrence of fragments 
of marine shells in the modified drift forming the fore-arm of 
cape ( 'od, where a great glacial river, flowing down from the 
melting of our continental glacier over the present Massachu- 
setts bay, brought these shell fragments from englaeial and 
finally superglacial drift like that which formed the shell- 
bearing till of drumlins in Boston harbor and its vicinity, de- 
positing them in the broad esker-like plateau of that pail of 
cape Cod, when the relations of the land and the sea level 
there were doubtless nearly the same as now. w. r. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Niagara Falls uml their History. By G.K.Gilbert. (National 
Geographic Monographs, prepared under die auspices of the National 
(deographic Society, vol. 1, no. 7. Sept.. 1895, pp. 203-236, with id fig 
urea in the text; American Book Co.; $1.50 a year, of ten numbers; 20 
cents each. 1 This paper is one of a scries written, so far as they appear 
in the first volume, by Major Powell. Professors Shaler, Russell, and 
Davis, and Messrs. Willis. Hayes, Diller, and Gilbert, designed to sup- 
ply to teachers and students of geography fresh ami interesting material 
with which to supplement the regular text hooks. 
The falls, the great gorge six and a half miles long, in which the river 
flows between the falls and the Niagara escarpment, the upper plain 
hounded by the escarpment, the lower plain adjoining lake Ontario, the 
method of the river's work in eroding the gorge, and its relationship to 
the Glacial period, are very clearly and graphically described. But the 
question whether a large part of the drainage now passing over Niagara 
falls was for a considerable time diverted through outflow from lake 
Huron east by lake Nipissing to the Mattawa and Ottawa rivers, as 
