20 PALEONTOLOGY OF NEW JERSEY. 
micaceous beds, and, although several are apparently identical with forms 
occurring in the Lower Marls, yet many of them are peculiar to these beds 
as far as represented in New Jersey. 
Above the Lower Marls come the Middle Marl beds, characterized by 
the yellow lime sands, filled in many places with Terebratula, and above 
this the layers at the base of the Upper Green Marls, which contain a 
fauna entirely distinct from those below, but still Cretaceous in its character, 
Again, at the summit of the Upper Green Marls we find another distinct 
fauna, representing the Eocene epoch of the more southern States and 
affording many species identical with those from Claiborne, Alabama. 
These mark six distinct zoological horizons, and if we divide the Lower 
Marls from the Crosswicks and Haddonfield beds, as will possibly be done 
when they are properly examined and studied, seven distinct horizons, six 
of which may be classed as Cretaceous and one as Eocene. 
These zoological horizons conform very closely, if not exactly, to cer- 
tain stratigraphical lines which were long since established by the State 
geologist under the names of Raritan Clays, Camden Clays, Lower, Middle, 
and Upper Marls, the last bed being mollusk-bearing only near the lower 
and upper portions, which are respectively Cretaceous and Eocene. The 
details of these beds can be found in the different annual reports of the 
State survey, particularly in that of 1868, and in that on the clays of New 
Jersey. 
Although between these zoological horizons there is little, and, indeed 
almost no interchange of fossils, the faunas being almost entirely distinct, 
the geological sequence is continuous, except between the Eocene or Upper 
layers of the Upper Green Marls and the beds immediately below, where 
there is a very slight unconformity, noticeable by close inspection, over 
a very limited area only, and consisting principally of a slight denudation 
of the top of the beds immediately below, before the deposition of the 
Eocene Marls. 
It is not necessary here to consider in detail the structure of the layers 
further than to mention that these different beds which are fossiliferous, 
or mollusk bearing, consist at the base of the section of beds of clay of 
