34 INTRODUCTION

toward their development hitherto. It is the intention of the State
Geological Survey to give this subject much attention, applying
various tests to these widely distributed products, so that the people of
the state may know their true value. There is little doubt but that
new deposits will be discovered, while other uses will be detected in
addition to those which are known to-day.

CLAYS. —There is perhaps no economic product which more largely
abounds in Maryland than clay, the importance of which has never
been fully appreciated hitherto. Millions of dollars are invested in
the clay industry in some of the states to the north of us, and there is
no reason to believe that their clays are in any way superior to ours.
The clays of Maryland are adapted to brick-making and pottery;
and some are admirable fire clays. The investigation of the prop-
erties of the clays has been hitherto very largely left to those who are
employed in the clay industry, and yet there is perhaps no product
which is more worthy of exhaustive scientific treatment. The clays
of Maryland occur chiefly throughout the southern and eastern por-
tions of the state and are found at several different geological horizons;
and others of acknowledged superiority are known in the older
formations of the western counties. Already there are between one
and two hundred plants in operation within the limits of the state,
but there is undoubtedly an opportunity for far greater expansion,
not only on the part of those already engaged in the business, but on
the part of those who are willing to establish new industries. The
State Geological Survey has in view a thorough study of the clays
of Maryland in the near future.

SANDS. —Large deposits of sand, both in unconsolidated form and
cemented into sandstone, are found both in the eastern and western
portions of the state. Particularly in eastern and southern Maryland,
beds of great thickness and wide areal extent are known. At a few
points work has already been done upon these materials and there is
already some market for the products. These various sand deposits
are useful for building and molding and also for glass-making. Their
development has only commenced, and it is the intention of the State
Geological Survey to look into their properties, and to indicate their
quality, quantity and distribution.