MARYLAND GEOLOGICAL SURVEY 219

furnace at Canton. They employ very largely the carbonate iron
ores which are obtained from the Arundel formation, mainly from
Anne Arundel and Prince George's counties. These great lenses of
carbonate ore have been worked since early colonial days, but an
ample supply still remains. Two types of ore are found in these ore
lenses known as the " white ore " or carbonate ore and the " brown
ore " or hydrous oxide ore.

Ores of iron are found widely distributed in Maryland from the
older crystalline rocks down to the more recent deposits, but the most
extensive accumulations thus far discovered are the brown hematite
and magnetite of Frederick county, the carbonate ore of Prince
George's county, and the iron ores belonging to the coal measures
of western Maryland. Under the present conditions of the iron
industry the Maryland ores have not the value which they once had,
although the excellent quality of the carbonate ores still makes it pos-
sible for them to compete with the cheaper materials of the west and
south. This carbonate iron has been largely used by the U. S. gov-
ernment, it being guaranteed to stand 30, 000 pounds to the square
inch in the pig, many tests giving 40, 000 pounds.

The great Maryland iron industries depend now to a very incon-
siderable extent upon local iron ores. The discovery of extensive
deposits in other sections of our country, particularly in Michigan,
Minnesota and Alabama, coupled with the wonderful extension and
cheapening of transportation, have resulted in the past few years in
driving out the charcoal furnaces and thus leaving no place for the
lean ores of Maryland.

The total value of pig iron produced from the Maryland carbonate
ore during 1896 was $115, 000. The other ores were not worked
during the past year.

THE COALS.

The coal deposits of Maryland are confined to western Allegany and
Garrett counties, and are a part of the great Appalachian coal field
which covers large portions of Pennsylvania, Maryland, West Virginia,
Kentucky, Tennessee and Alabama. In the northeastern portion
of this area the rocks containing the coal have been thrown into a