MARYLAND GEOLOGICAL SURVEY 193

The fossils are quite distinct from those which are found in the
Patapsco formation and abound much more largely in dicotyledonous
types of vegetable life. Most of the species are identical with those
found in the Amboy clays of New Jersey which form the northern
extension of the formation as developed in Maryland.

THE MATAWAN FORMATION. —The Matawan formation receives
its name from Matawan creek in Monmouth county, New Jersey,
where the deposits of this horizon are typically developed. It is the
most widely extended of the upper Cretaceous formations and reaches
from the shores of the Raritan Bay across New Jersey, Delaware and
Maryland to the Potomac river. Throughout Virginia it is buried
beneath later deposits which have transgressed it, but it reappears
again in the Carolinas. Within the limits of Maryland it forms a
narrow belt which crosses southern Cecil and northern Kent counties,
and then reappears upon the western shore of the Chesapeake in
eastern Anne Arundel county, and thence continues southwesterly
with constantly narrowing confines across Anne Arundel and Prince
George's counties, during the latter part of its course appearing as a
narrow band along the westward face of an ill-defined escarpment.

The deposits of the Matawan formation consist mainly of dark
colored micaceous, sandy clays, which are generally argillaceous in
their lower part and sandy toward the top. Upon the eastern shore
of Maryland the Matawan formation has a thickness of very nearly
100 feet, but it has already considerably declined in eastern Anne
Arundel county, where it is about 50 feet, and thence continues to
decrease southeastward, until in the vicinity of Fort Washington it
has declined to 15 feet in thickness, as a result of the gradual trans-
gression of the Eocene deposits.

The fossils of the Matawan formation are highly characteristic of
its upper Cretaceous age. Numerous marine mollusca, among them
several species of characteristic ammonites, are found among its fauna.
Some of these forms range into the next succeeding Monmouth forma-
tion, but many are restricted to the Matawan.

THE MONMOUTH FORMATION. —The Monmouth formation, so
called from its typical development in the region of the Monmouth