The mean temperature for eastern Mary land for spring is 51.7° F.; for summer, for autumn, 55.8° F; for winter, 36.1° F.; for the year, 54.5° F. ' • for southern Maryland, 53.1° ; 75.5° • ; 36.9° ; 55.6°; for north ern central Maryland, 50.6° ; ; 54.3'; 33.1° 53*; for western Maryland, 49.4° ; 72.7° ; 52.7° ; 31.7° ; 52°.
Maryland displays a remarkably complete sequence of all the geological founda tions. The most ancient rocks are here to be found, as well as those still in the process of deposition, and, between these wide limits, al most every important geological epoch is rep resented. In the Coastal Plain, a predominance of tertiary foundations is found on the Eastern Shore, and, of Mesozoic and Tertiary beds, on the Western Shore. There are few rocks, the country being overlaid with deposits of sand and• gravel. In the Piedmont region, on the eastern side of Parr's Ridge (its central water shed), there is a sequence of highly crystalline rocks, in large part, igneous in their origin. On the western side of the ridge, the rocks are only partly crystalline and represent the early Paleozoic time. The rocks of the Frederick Valley are composed of blue Paleozoic lime stone, in part overlaid by red sandstone. The Blue Ridge is made up of Cambrian and Lower Silurian beds, in places so eroded and displaced as to disclose the Archaean floor upon which they rest. The Appalachians proper are made up of sharply folded Upper Silurian and De vonian strata, and the Allegheny Plateau is mainly composed of late Devonian and Car boniferous deposits, containing the coal seams of the Cumberland Mineral Resources.– Maryland is rich in mineral resources. Iron ore is extensively dis tributed throughout the Western Shore and in the northern part of the Eastern Shore, and is of good quality for casting and other purposes. The iron industry is of early origin. Forges and furnaces were in operation in the province as early as 1649, and the industry continued, until a recent date, to be an important factor in the prosperity of the State. Most of the old furnaces now have been extinguished, being unable to compete with the great iron and steel plants, using ores produced in foreign countries or in distant parts of the United States. The seat of the steel industry of the State is at Sparrow's Point, in the great works begun in 1887, where Cuban ores are chiefly used, mixed with those from Spain and Al geria. The first Bessemer steel ever produced in Maryland was made there 1 Aug. 1891.
The coal deposits of Maryland belong to the Allegheny field and are semi-bituminous, supe rior to any other for generating steam. The portion of this field lying in Maryland is of comparatively small size, but constitutes by far the most important of the State's mineral re sources. It is called the Cumberland, Frost burg or George's Creek Basin. Situated in an elevated trough, west of the city of Cumberland, and between Dan's and Savage mountains, it is about 20 miles long and 4 miles wide. The principal coal bed is known as the Big, or 14-foot, Vein, and has been the chief one worked. Nearly 100,000,000 tons of coal have been -hipped from this vein. The coal contains fron 72 to 83 per cent of carbon, and its dis cove v. about 1804, gave a strong stimulus .0 the movement fur the construction of the Chesa peake and Ohio Canal and the Baltimore and Ohio Railroad.
Three veins of copper are found in Mary land and, before the opening of the Western copper mines, they made it a copper-producing State. Chrome deposits were discovered in Baltimore County in 1827 and have been exten sively worked. Some gold has been mined in Montgomery County.
Extensive areas of granite have been quar ried for building stone, especially at Port De posit, in Cecil County; near Woodstock in Bal timore County (much used in the public build ings in Washington city); and near Ellicott - - linty. Gneiss has been guar County. The sandstone . of Seneca Creek in Mont -A' important and their prod •much used in Washington city.
_erbest-known districts in the United tor the production of roofing slate is _ 'Peach Bottom region in Harford County, sear the Pennsylvania line. These slates were worked as early as the American Revolution. The most valuable limestone deposits are the highly crystalline marbles at Baltimore County, lying in a bed extending from Lake Roland through Texas to Cockeysville. These quarries produce the white steps for which the Balti more houses are noted. The Washington Monument in the District of Columbia was built of stone from the Cockeysville quarries. Some of the Maryland marbles have decorative possibilities, and the °Potomac marble) or °Cal ico rock') of Frederick County is used in the old House of Representatives in the National Capitol. Maryland limestone is used as flux for blast furnaces and is largely quarried and burnt to produce quick lime for commercial and agricultural purposes.