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with a film of paraffin. The former method, therefore, considers the specific gravity of the clay to be the same as its mineral grains, while the latter method considers the pore spaces between the grains as a part of the clay mass, and the specific gravity depends consequently both on the porosity and mineralogical composition.

PART II.

THE STRATIGRAPHY OF THE NEW JERSEY CLAYS.

By HENRY B. KÜMMEL and GEORGE N. KNAPP.'

'The stratigraphy of the South Jersey clays is based largely upon the field work of G. N. Knapp, whose familiarity with the deposits of that portion of the State has been of great assistance both in locating clay deposits and in their correlation. The senior author, however, is responsible for the presentation of these facts as here given.

CHAPTER V.

THE POST-PLEISTOCENE CLAYS.

CONTENTS.

Geological distribution of clays.
Post-Pleistocene clays.

Character.
Location.

Clay loams.

GEOLOGICAL DISTRIBUTION OF CLAY.

The clays of New Jersey belong to a wide range of geological formations, occurring in fact in nearly all the larger geological subdivisions in the State. They are not all of equal value, however, and in the following table, which shows the major geological subdivisions of the State, only the important clay-bearing members are indicated by the asterisk. Small clay deposits, some of which are worked, occur in most of the other groups, as will be shown in the following pages.

[blocks in formation]
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