64 Discovery of Stone Implements in [January, 
deposit. It contains a mixture of all the various rocks over 
which the glacier of the Delaware would pass ; those from 
the Hardest formations being most abundant, as they would 
best survive the severe abrasions to which they had been 
subjected. 
No implements are yet reported from this bed, so that, 
putting aside the disputed implement from the morainic 
accumulation at Butzville, we have no evidence at present 
that man frequented the valley of the Delaware before or 
during the greatest extension of the glacier of that valley. 
The deposits from which Dr. Abbott has obtained the imple- 
ments lie above this great unstratified bed of rounded drift, 
and we should have great difficulty in fixing the approxi- 
mate age of the implement-bearing strata if it were not for 
the fortunate occurrence of the sandy clay with large 
boulders (No. 1 in Figs. 1 and 3) clearly superimposed on 
the latter. We may now turn our attention to the consi- 
deration of this surface-bed and the relation it bore to the 
Glacial period. 
In my discussion of the glacial and post-glacial pheno- 
mena bearing on the date of the excavation of the gorge at 
Niagara, published in this Journal,* I have described the 
occurrence of large boulders of crystalline rocks lying above 
all the other glacial beds. In the till which lies next the 
glaciated bed-rocks the stones are all of local origin ; in the 
surface deposit they are all from the distant north. 
Prof. James Hall, so long ago as in 1843, had fully recog- 
nised the importance of the occurrence of these far-trans- 
ported blocks that lie scattered over the surface, and had 
noted the difference in the mode of their occurrence and in 
their composition from the rocks included in the lower 
glacial beds.f He shows that the glacial beds belong to 
two periods : one, the lower, which contains mostly local 
rocks ; the other, the upper, containing far-transported crys- 
talline rocks. He says that on the broad northern slope 
towards Lake Ontario, where hills are distant, there are 
numerous and extensive fields of boulders resting upon the 
surface, or but partially imbedded in the soil, and holding 
such a position that it is evident that they are of subsequent 
origin to the great body of detritus ; and again, on the 
western prairies, long lines of boulders are to be observed 
stretching away for miles beyond the reach of vision, as if 
once forming a line of coast or deposited along some channel 
* Op. cii.y April, 1875. 
f Geology of New York, Part IV., pp. 319 to 321. 
