North Atlantic Pleistocene Problem — Shattnck. 93 
ing-ton. three or four miles southwest of Trenton ^' * * 
the writer found similar deposits at Bridgeport, Pa., opposite 
Norristown, still further south. * '•' * Glaciated boulder- 
ets were here taken from clay of such character that, were the 
locality known to have been covered by ice, its reference to till 
would be fully warranted. Bridgeport is about 50 miles south 
of the terminal moraine. 
"It is not intended to convey the impression that every re- 
gion where glaciated stone may be found was necessarily once 
covered by glacier ice. The possibility of transportation of 
glaciated material beyond the edge of the ice by water, is dis- 
tinctly recognized. But it is not believed that water alone, or 
water-bearing glacially-derived bergs could produce all the 
results which are here recorded. Neither the structure of the 
extra-morainic drift, nor its physical make-up, nor its geo- 
graphic or topographic distribution, is consistent with such a 
hypothesis. 
"At several points in New Jersey south of all the localities 
thus far mentioned within the state, there are topographic feat- 
ures which are easy of explanation if ice once extended to the 
region where they occur, but which seem to be very difficult of 
explanation on any other hypothesis. The features here re- 
ferred to characterize the region from Washington, ^liddlesex 
county, southwest to Fresh ponds and beyond, and also the 
region east of Trenton, from White Horse to Hamilton square. 
The topography in these regions is very much like that of a sub- 
dued terminal moraine." 
In his report for 1892, professor Salisbury discusses at 
some length the character and origin of the Trenton gravel ; he 
shows very plainlv that it was a valley train deposited by the 
Delaware river from materials washed from the glaciated re- 
gions, and states that it was deposited "during that stage of 
glaciation when the ice edge stood near Belvidere." He then 
discusses the Yellow (Jravel formation of professor Cook and 
shows that it recorded a most complex historv. His con- 
clusions may be summarized as follows : 
First. "The time of deposition of the original yellow grav- 
el." This covers the period when the country was sufficiently 
low to allow the gravel to accumulate on hills which are now 
nearly 400 feet high, at least south of Matawan. Age pre- 
Pleistocene. 
