MARYLAND GEOLOGICAL SURVEY 35

PORCELAIN MATERIALS. —The porcelain materials of Maryland,
which comprise flint, feldspar and kaolin, have been relatively little
worked, although it seems probable that valuable deposits of these
materials may be looked for in many portions of the Piedmont belt.
Their manner of occurrence in crystalline rocks is such that close
examination is necessary for their accurate location, but the proposed
investigation which will be given to the whole crystalline area will
undoubtedly develop many new deposits of these materials.

MARLS. —The marl deposits of Maryland have been worked from
time to time for nearly a century. They received the attention of the
First Geological Survey and of the subsequent State Agricultural
Chemists, and since then analyses have been made from time to time
by the chemist of the Agricultural Experiment Station. It is desir-
able that this work should be continued and that the location and
extent of these marl beds, which cover so wide an area in eastern and
southern Maryland, should be fully determined. It is particularly
important that the agricultural interests of the counties where these
natural fertilizers abound should realize the value of their own
resources.

IRON ORES. —The iron ores of Maryland have from the earliest
times been a source of great profit to the state of Maryland. The
earliest blast furnace was built within the limits of the state, and
local ores since early colonial days have been smelted both in Mary-
land and adjacent states. On account of the discovery of larger and
more easily worked deposits in other portions of the country, the iron
industry in Maryland has in later years suffered a considerable decline,
but notwithstanding these facts extensive deposits are still known to
exist, and the carbonate ores are to-day worked with profit. The
State Geological Survey has in view the location and study of these
deposits with the view of bringing them to the attention of the people.

COALS. —The coal deposits of Maryland have perhaps been more
fully explored and extensively worked than any other of our mineral
resources. In Allegany county, especially, the coal operators are
well informed as the result of private enterprise, regarding their coal
seams, but in Garrett county little has yet been done toward the devel-