Atlantic Highlands Cretactic — Prather. i67 
in this bed which are of secondary origin. Many samples 
of the Navesink are made up almost entirely of glauconite 
grains with only enough fine material to hold them together. 
The glauconite grains may be only slightly altered but in 
some instances (sample A 1 ) they are changed to a dark 
brown color, when it takes a good magnifying glass to dis- 
tinguish them. In this sample mica is found and there are 
some quartz grains which are larger and more rounded 
than one would ordinarily expect from the sample. The 
samples grade from almost pure glauconite to no glauconite 
grains at all, and mica is generally absent but may be in 
certain cases abundant. The amount of quartz is variable, 
ranging from 50% to zero. The feldspar though present 
only shows in the thin sections as it is too opaque to be 
told without grinding down the sample. 
The Navesink is marked by a fossil bed near its base 
which bed is very persistent along the whole section, and 
care should be taken not to confuse these fossils and assign 
them to the beds underneath as has sometimes been incor- 
rectly done by some of our best workers. 
It is to be noted on the whole that in the samples taken 
much glauconite is found. Besides this many fragments of 
the older rocks, or land derived material, occur, indicating 
a near shore deposit. There is much argillaceous material 
to be found in the samples. The upper part contains more 
land derived material and mica flakes, and arenaceous mate- 
rial is more common in this part. The principal fossil bed 
which is designated as bed 3, is the lowest of the three 
beds which contains the fossils.* It is of varying thickness, 
generally about 3 feet thick, but often as thick as 10 feet. 
This lower fossil bed is in some places found where the 
two beds, bed 1 and bed 2, are missing. It generally con- 
tains a considerable amount of indurated material. The 
color of the Navesink beds is generally darker than those 
of the Matawan, and they contain more glauconite and less 
fine material and do not contain the layers and pockets of 
sand or of clay, which characterize the Matawan formation. 
There is an uncomformity between the Navesink and 
the Redbank showing that erosion has taken place. This 
* For a list of species see below. 
