MARYLAND GEOLOGICAL SURVEY 153

GEOLOGY.

The geology of Maryland as well as its physiography shows an in-
timate relationship to the adjacent areas upon the north and south,
so that its complete interpretation can be gained only by taking into
consideration the great eastern border region of which the state is not
only geographically but geologically a part. Frequent reference will
therefore be made in the succeeding pages to the general distribution
and relations of the geological formations found represented within
the limits of the state, although the detailed descriptions will be con-
fined to those features more particularly characteristic of the Mary-
land area.

The state of Maryland is so situated. as to display, in spite of its
comparatively small size, less than 10, 000 square miles of land area,
a remarkable sequence of geological formations. The most ancient
rocks which make up the earth's crust as well as those still in the pro-
cess of deposition are here found, while between these wide limits
there is hardly an important geological epoch which is not represented.
It is doubtful whether another state in the Union contains a fuller his-
tory of the earth's past. To make the completeness of this record in
Maryland somewhat more intelligible it is well to consider the basis
on which geologists are able to determine the succession of deposits.

Geology in its broadest aspects must be regarded as the science of
the earth from its very earliest beginnings down to the present day,
and as such stands in close relationship to the science of astronomy in
its study of the origin of the solar system. In the absence of a more
satisfactory theory, most geologists to-day are prepared tentatively to
accept the nebular hypothesis of Kant and Laplace as a starting point
in earth evolution. This hypothesis supposes that the nebulous, gas-
eous mass out of which the planetary bodies were formed embraced
the most distant orbit of the solar system. As condensation began,
successive rings were thrown off, which by further condensation pro-
duced the several planets of our system. These in turn may also
possess rings or satellites, as with Saturn, or these rings may condense
to form a single satellite, as in the case of our Moon. The natural