94 The American Geologist. August, looi 
Second. "An epoch of elevation and extensive erosion. 
This covers a period when the yellow gravel was raised and the 
land surface greatly eroded. 
Third. "An epoch of depression." This embraces a period 
when central and southern New Jersey was 150 feet lower than 
now. This depression is correlated with the first glacial epoch 
and is also tentatively correlated with the Columbia. 
Fourth. "An epoch of elevation and erosion." During 
this time the land was raised to a greater bight than before and 
the streams cut deeper valleys than during the early epoch of 
elevation. 
Fifth. "An epoch of slight depression." Correlated tenta- 
tively with the last glacial epoch and also was the period when 
communication was established between Raritan bay and 
Trenton. 
Sixth. "Subsequent elevation." An elevation of 40 to 60 
feet followed by the present subsidence. 
Professor Salisbury in his report for 1893 divides the yel- 
low gravel for the first time into four well-defined periods : the 
first and the oldest he calls the Beacon Hill ; the second, Pen- 
sauken ; the third, Jamesburg ; and the fourth is left unnamed, 
but later, in a subsequent publication, is called Cape May. 
The Beacon Hill formation appears to be Miocene, and 
therefore, will not enter further into our discussion of the 
gravels. 
According to professor Salisbury, the Pensauken was de- 
posited in valleys cut out during the post-Beacon Hill elevation. 
It is considered to be an aqueous formation, and its distribution 
indicates that the land was submerged 200 feet during its depo- 
sition. One of the chief diagnostic features of this formation 
is the presence of decomposed boulders of gneissic and granitic 
material found imbedded in its mass. The formation ranges 
in elevation from 200 feet at Perrineville to 80-00 feet south of 
Palmyra. The elevation is also regarded as being more in the 
region of Beacon Hill than elsewhere. At South Amboy its 
presence is indicated at an elevation of 147 feet. 
The name of the formation is derived from Pensauken 
creek, but the statement is made that the formation is most 
characteristic near South Amboy, and that the latter locality 
would have'been chosen to typify the formation were it not for 
its association with the plastic clays. 
