574 FRANK CARNEY 
From it most of the calcareous matter has been leached.”* ‘The 
constitution of the drift is, in a general way, comparable to that of the 
younger drift. It contains materials of all grades, from huge bowld- 
ers to fine clay.’ ‘Limestone is rarely present. When the drift 
occurs in quantity, glaciated stones are by no means rare.”’? “It 
generally lacks all indication of structure, though foliation is to be 
seen in some of the deeper exposures.” ‘‘In its constitution, and in 
the relations of its constituents, the drift corresponds with till.’’ 
It should be noted, however, that Salisbury does not find the extra- 
morainic drift in New Jersey uniform in the stage of weathering 
attained; for this reason he suggests that, while most of it probably 
corresponds to the Kansan, it is possible that a younger pre- Wisconsin 
drift may be represented.* 
Geographical jactor—The above descriptions of drifts pertain to 
deposits more or less distant from central New York. The diversity 
in the stratigraphy and topography of northern North America 
introduces other considerations that may render these descriptions 
only partly applicable to other regions. Similarity of glacial deposits 
elsewhere may result only from identity (@) in the stratigraphical 
terranes which furnished the débris; (6) in the period and conditions 
of weathering to which the débris was later exposed; (c) in the suc- 
cessions of ice-invasions; and (d) in the distance of the sections being 
compared from the termination of the particular sheet in question. 
It is evident, therefore, that in New England, New York, Pennsyl- 
vania, and New Jersey specific drift-sheets may have somewhat 
different features than have been reported by investigators elsewhere. 
TOPOGRAPHIC CONTROL OF THE EROSION AND DEPOSITION OF DRIFT 
In general.—It is probable that the main dissection lines of the 
Finger Lake area even before the earliest glaciation were north-south 
valleys; the troughs of the present lakes, their tributaries, primary, 
secondary, and lesser, had developed a variety of transverse valleys. 
So in whatever direction the ice-mass moved there must have been 
localities, of rather limited extent, where ice-erosion was less active; 
tR. D. Salisbury, Glacial Geology, Geological Survey of New Jersey, Vol. V 
(1902), p. 174. 
2 [bid., p. 188. 3 Ibid., p. 757. 4 Ibid., p: 769. 5 Ibid., p. 782. 
