Vol. 58. ] GLACIER-LAKES IN THE CLEVELAND HILLS, 473 
refer especially to Prof. R. 8. Tarr’s brief but highly interesting 
account of the lakelets that fringe the Cornell Glacier on the 
Nugsuak Peninsula.’ Prof. Tarr furnishes a description of the 
deltas and floor-deposits of these lakelets, which will be found 
of great value for comparison with the relics of similar lakelets in 
Britain, 
III. Pretstocenr Lakes, AND THE CRITERIA FOR THEIR RECOGNITION. 
It might have been predicted that proofs would be forthcoming 
that extra-morainic lakes of Pleistocene age had prevailed over areas 
extensive in proportion to the great magnitude of the ice-sheets. 
Traces of several such lakes have been recognized, the most important 
of which is, undoubtedly, the gigantic Lake Agassiz, the waters of 
which covered half a million square miles in North America. This 
lake has a claim to consideration, apart from its mere magnitude, as 
it appears to have been first in order of discovery as well as in point 
of size. Keating inferred the presence of a lake on this site so 
long ago as 1823, but probably to Gen. Warren should belong the 
eredit of clearly demonstrating its existence. A noteworthy series 
of lesser lakes in the neighbourhood of Rochester (N.Y.), has 
been well described by Mr. H. L. Fairchild,’ and the investigations 
of Prof. G. K. Gilbert upon a similar series have been referred to. 
Many other examples in North America have been described. The 
only lakes having such an origin that have been recognized 
in this country, so far as I am aware, are:—a lake enclosed in 
the valley of the Black Cart, behind (south of) Glasgow, identified 
by my lamented friend the late Mr. Dugald Bell of Glasgow,’ and 
independently by Prof. James Geikie*; another in the valley of the 
Tweed, also discovered by Prof. Geikie’®; the Glen-Roy Lakes, 
the lacustrine nature of which was first conclusively shown by 
Mr. T. F. Jamieson’; a great lake in the Vale of Pickering, 
postulated upon very inconclusive grounds by Phillips and other 
writers, but demonstrated in a very clear and convincing manner 
by Mr. C. Fox-Strangways’; and a great series of extra-morainic 
lakes described by the late Prof. Carvill Lewis.° 
The criteria by which ancient extra-morainic lakes can be 
recognized are mainly four :—(1) beaches; (2) deltas; (3) floor- 
deposits ; and (4) overflow-channels. But to these might be added 
the @ priori arguments of Prof. Carvill Lewis, who considered that 
the existence of lakes could be deduced from the ascertained position 
of the ice-front, a process of deduction upon which I have never 
relied, except when reinforced by the direct testimony of one or more 
Amer. Geol. vol. xx (1897) pp. 150 e¢ seqq. 
Am. Journ. Sci. ser. 4, vol. vii (1899) pp. 249-63. 
Trans. Geol. Soc. Glasgow, vol. iv (1874) p. 66. 
‘Great Ice Age’ Ist ed. (1874) pp. 186 et seqg. 
Ibid, 2nd ed. (1877) p. 144. 
Quart. Journ. Geol. Soc. vol. xix (1863) p. 235. 
Mem. Geol. Surv. ‘ Jurassic Rocks of Britain’ vol. i (1892) p. 423. 
Rep. Brit. Assoc. 1887 (Manchester) p. 692. 
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