278 Schermerhorn—Northern and Northwestern Lakes. 
different long bays than at their mouths; so with the margin of 
the Hsker sea, it rises as it is followed up the valleys. In some 
exceptional cases, as in the County Wicklow, the marginal 
beach of the Esker sea is at an excessive height. But these 
excessive heights are south of a regular line, they gradually ris- 
ing from the west, eastward; while south of that line they do 
not rise. Therefore it seems evident that the line is a fault 
north of which the land to the eastward rose considerably more 
than to the westward, subsequent to the accumulating of the — 
Esker drift. The details of this phenomenon are fully given in 
the Geology of Ireland and need not be here repeated. 
The regular relative heights at whrch the true Esker drift 
terminates seem to me to be positive proof that it must be an 
adjunct of a widespread action lke that of a sea which had com- 
parative level margins, and not to an erratic water supply like 
that due to the melting of an ice sheet or snow field, either of 
which is necessarily “ martyr to circumstances,” sometimes low, 
at others high. I would suggest that before positive statements 
are made in connection with the ¢rue Irish eskers—that it 
should first be learned what is a true esker. 
Art. XXXII.—Physical Characteristics of the Northern and 
Northwestern Lakes; by L. Y. SCHERMERHORN, C.H. 
In the following memoranda an attempt has been made to 
assemble a part of the latest and most reliable information re- 
lating to the Great Lakes. The lately completed lake surveys, 
made by the United States, have reduced to exactness much 
that previously was only approximate and the perfection 
of methods used give a perfection to the results which seldom 
obtains in surveys covering so great geographical extent and 
involving so many details. 
The water surface of the Great Lakes with the land draining 
into it presents a total drainage basin of over 270,000 square 
miles, assembled as follows: 
Area of water Area of water Aggregate area 
surface, shed, of basin, 
square miles. square miles. square miles. 
IhakeySupenlons 5442s ae eee 31,200 51,600 82,800 
StiMary’s Rivers2fo2e 0212 s223 150 800 950 
ake Michi oan as ae hee 22,450 37,700 60,150 
Lake Huron and Georgian Bay - 23,800 31,700 55,500 
Site, Clenie Isinveie Shes cade bees ee 25 3,800 3,825 
Makes tC lain: 92 hems susie eee 410 3,400 3,810 
ADEUTOUH TUNG Soe soos ee Boose 25 1,200 1,225 
Teak @ abies s/c tay ape ch 9,960 22,700 32,660 
Niagara Rivensosa cee as =a 15 300 315 
Wake Ontario..--.------------ 7,240 21,600 28,840 
95,275 174,800 270,075 
