360 THE JOURNAL OF GEOLOGY. 
geological column is lacking, there are reasons for believing that in 
part at least, it is Miocene. The last subdivision of the Yellow Gravel 
is thought to have been either contemporaneous with the last glacial 
epoch or more recent. j 
In reference to the length of time represented by these deposits, 
it is stated that the interval between the first and second divisions 
was probably much longer than the time which has elapsed since 
the second; and that the interval between the second and third stages 
was longer than the time since the third. 
The relation of the later phases of the Yellow Gravel to Pleistocene 
glaciers, and the probability that the Jamesburg formation at least was 
deposited in part through the agency of floating ice, and possibly in 
the vicinity of glaciers, are discussed and the weight of the evidence 
indicated. The presence of a great variety of rock materials, including 
large bowlders, in the Pensauken, and the occurrence of that deposit 
beneath “extra-morainal glacial drift,” seems to suggest that there 
may have been a time of glaciation of older date than the earliest evi- 
dence of glacial work otherwise recognized in the region studied. The 
absence of glaciated stone from the Pensauken, makes it impossible to 
connect this formation with the ice with any degree of certainty. 
Extra-morainal drift-—The true nature and significance of certain 
detached areas of much weathered morainal material, south of the great 
terminal moraine that crosses northern New Jersey, has been the source 
of controversy, but the mass of evidence presented in the report before 
us must silence opposition, as the glacial origin of the material referred 
to is placed beyond all doubt. The distribution of this extra-morainal - 
drift from the Delaware eastward, for about halfway across the state, is 
accurately mapped, but its extension in the lower country to the east- 
ward is indefinite and seemingly indeterminate. Its maximum extent 
south of the terminal moraine is twenty-two miles, and the area more 
or less completely covered by it, about 450 square miles. This older 
drift occurs in detached areas and bears evidence of marked decay and 
extensive erosion. A large part of the region it once covered retains 
only scattered bowlders to show the nature of the former covering. The 
southern limit of the ice during this earlier invasion is approximately 
indicated on a large scale map which also presents much additional 
data concerning later glaciai deposits. 
The care with which the distribution, character, weathering, erosion, 
etc., of the extra-morainal drift has been studied and the amount of 
