i8 
Frank Carney 
New Jersey described by Salisbury. Nevertheless, this feature 
does not preclude identity of epochs, since the latter drift, which 
was never covered by a later till-sheet, has been subject to agents 
of disintegration during a period that has sufficed for the develop- 
ment of a well-advanced drainage system, the major streams hav- 
ing attained “levels more than loo feet below the levels of the S 
lowest summits on which the drift occurs. 
I 
SUMMARY. I 
This old drift, where now exposed, with one doubtful exception, j 
is fresh in appearance; is very compact in structure, sometimes j 
foliated; its bowlders preserve striae; its upper surface shows j 
erosion, presumably somewhat beyond the removal of the weath- 
ered horizon which may be the source of some of the rather rotten 
crystallines now mingled with the recent drift.^^ 
Geological Department, Denison University, December, 1906. 
I 
I 
I 
R. D. Salisbury, loc cit., p, 759. | 
^ The writer has just noted Gilbert’s paper, “ Bowlder-Pavement at Wilson, [ 
N. Y.” (this Journal^ voh vi [i 8 g 8 ], 'pp. 771-775)* The pertinent feature of this | 
paper is the recognition of the possibility of two till-sheets, and of the certainty of j 
‘‘an epoch of local till-erosion by a glacier. The epoch may be a mere episode 
interrupting a period of till deposition by the same glacier, or it may be a part of a 
stage of re-advance following a long interglacial period” (p. 774). 
