18 Th(^ Aiix'^ricdii GeologiM. jMnnnrv, \m^ 
preliniiiiiir\ (Ictcriniiiat ions wt'rc m.-idf liy liiiii. The rcrcfciict' to the 
work of Wliittlescy (p. IHU) is siicli :is to Lcivc rlu' iiDju-cssioii (liat he 
liacl fully understood and intorprctt'd t in' "kett lo rjingc" of eastern 
Wisconsin. Col. Wliiltlesey was, we believe, the first to recofini'/.e its 
j^iacial orif^in. hut we believe lie did not go further. ^Nfany otlier 
illustrjitions of inaeeurjite statements of the views and works of others 
mighl i)e cited. These tilings iire of importance to the public chiefly 
in showing the carelessness with which the book has bt^en prepai'ed. 
It is no exaggeral ion lo say that I'acisare no more carefully dealt 
with than authors. ( )f this, more than one instance has already been 
pointed out. We take s|)ace for l)nt a single further illustration, 
'i'liis is the map of tin* Trenton gravels, and thi' statenn^nts conceiwi- 
ing the Pleistocene format ions along the Delaware. This is critical 
ground for the <|ue.<tion announced in the title of the volume. The 
Trenton gravels are ma])ped as extending north-ward beyond the 
confines of New Jersey. They are majijied as extending something 
like ten miles below Trenton on the New Jersey side of the river. 
The Trenton gi'axcls, |)rop(^r!y s|)eaking, <lo not ext(Mid north of F»el- 
videre. whi're the terminal moraine crosses tin* Uelaware. There is 
gravel in the helaware \alley north of that point to be sure, but it is 
of much later origin than that at Trenton. That at Trenton is of 
ecjnal age with the gravel of the dissevered terrace reaching as far 
north as Uelvidere. but no further. Its e(|uivalent doubtless exists 
along the 1 )elaware to the south. But it has not been defined. If 
the sand and gravel of the area ma|)ped as Trenton gravel below 
Trenton be really its <M|uivalent. tlien the urea runs much further 
south. Hut we think Prof. AV right has given no attention to this 
question, anfl that he is not attem])ting a new mapi)ing. The Trenton 
gravel was, w<* are confident, deposited not "when the ice liad. 
melted far back towards the head-waters of tlw i>elawa.re" (p. 261 ), 
but during tlie last glacial epocli wliile the ice edge stood at Belvidere, 
Prof. Wright's conclusion as to the time of deposition of the Trenton 
gravels is forced upon Jiim by liis adherence to the doctrine of but one 
ice-epocli. There are the troublesome l*hiladel|)hia brick clays 
(Columbia) which even Prof. Wright recognizes as much older than 
the Trenton gravels, to be accounted for. If the two formations 
ratist be included Avithin the limits of one ice-epoch, it is no wonder 
that the origin of the latter is assigned to a date much later than that 
of the inoraiTie, even if the facts of Their stratigraphy must be 
neglected to get them there. There is really no area with which we 
are familiar where the evidence for more than one ice-epoch during 
the glacial period is stronger than in the Delaware valley. If I'rof. 
Wright does not see it there, he is not likely to see it elsewhere. 
Such an expressitm as "glaciated driftless area" and such a state- 
ment as that "the transporting capacity of water is in inverse ratio 
to the sixth power of its velocity" (p. 53), are to be noted only to se- 
cure their correction in future editions. They are mere slips. Per- 
haps the reference (p. 69) to "gneiss," "containing beautiful crystals 
of porphyry" belongs in the same category. 
