of the estuaries navigation is blocked on all the rivers at the Fall Line, where the streams fall over the escarpment of the Piedmont Plain. The only lake in Virginia is Drummond Lake, situated in the centre of the Dismal Swamp (q.v.), in the southeastern corner of the State.
Climate. East of the Blue Ridge the climate is mild or temperately warm, with a mean temperature of 37° for January and 77° for July. The minimum here rarely falls below 10°, while the maximum may reach 110°, though it is generally about 100°. In the uplands the climate is dry and healthful, but malarial diseases are endemic in the tidewater section. West of the Blue Ridge the summers are cool and very pleasant, while the winters, especially on the mountains, are cold. The mean temperature at Staunton, in the Great Valley, is 33.4° for January and 74.6° for July. The minimum in this section may reach 8° below zero. The rainfall is sufficient throughout the State, and favorably distributed for agriculture. It is greatest in the central portion near Richmond, where the average is 48 inches. In the Great Valley it is 38 inches.
Soil and Vegetation. The soils of eastern Virginia are in general light and sandy, except in the bottom lands and in the marsh regions, where a deep layer of vegetable mold has accumulated. In the Piedmont upland the soil is generally more fertile, having been enriched by decayed greenstone material. The most fertile portion of the State, however, is the Great Valley, where the underlying rocks are ancient limestones, whose decomposed materials are admirably adapted for wheat and other grain. The forests are still of considerable extent, and consist in the coastal plain chiefly of yellow pine and cedar, with cypress in the swamps and some oak, hickory, locust, and persimmon. In the western uplands there are large forests of deciduous trees, with white pine on the mountains, and with the general characters of the Appalachian floral region. See paragraph Flora under United States.
Geology and Mineral Resources. As in the other Atlantic States, the principal geological formations run in parallel bands from southwest to northeast, and correspond closely to the topographical regions, whose characteristics, in fact, are dependent upon the underlying rock formations. The coastal plain or tidewater section is overlaid by unconsolidated strata of sand, gravel, clay, and marl of Tertiary and later origin. The western boundary of the coastal plain formation runs from the neighborhood of Washington due south, passing west of Richmond. Between this line and the Blue Ridge the country is of Archæan origin, consisting of granite, gneiss, syenites, and slates, with intrusions of greenstone in the west. The central part of the region, however, was submerged in early Mesozoic times, and several large patches of rock belonging to the Jura-Trias system still remain. The Blue Ridge consists mainly of Potsdam sandstone of the Canadian system, and the valleys and ridges to the west of it are of Lower Paleozoic age, Silurian limestone predominating in the valleys, and Devonian rocks on the ridges. A peculiar feature of the limestone region in the Great Valley is the formation of great caverns which rank among the foremost natural curiosities in the country, such as Weyer's Cave in Augusta County, and the arched remnant of a cave, famous as the ‘Natural Bridge,’ in Rockbridge County.
Virginia has a great and varied mineral wealth. Iron is found as magnetite along the eastern base of the Blue Ridge, limonite on its western slope and in various other localities, and red hematite in the western Alleghanies. Other metals found in the mountain region are zinc, lead, tin, and copper, and manganese is widely distributed. Through the Archæan rocks of middle Virginia runs an auriferous quartz reef, and silver is also found in small quantities. Building stones, granite, limestones, and sandstones are found of great beauty and variety, and in inexhaustible quantities. Hydraulic limestone is also abundant, and in the southwestern corner of the State there are immense ledges of gypsum and rock salt. Even the tidewater section contains valuable minerals in the form of greensand marl.
Mining. The mining industry has never reached any great development, but it has, nevertheless, for a long time been an important factor in the industrial history of the State. Coal (mostly bituminous) is mined in the Appalachian region. The total product of the State, as reported for the year 1882, was 112,000 tons, and increased to over 1,000,000 tons for 1888. There was then a steady decrease of product until 1892, when it fell to 675,205 tons. Subsequently, however, extensive developments in Wise County brought up the annual output again to more than 1,000,000 tons. Some of this product is used in the making of coke. The output of iron rose in 1900 to 490,000 short tons. Almost all of this was brown hematite, constituting one-half of the country's output of that ore. Considerable quantities of stone, principally granite, limestone, and slate, are quarried in the central and Piedmont districts. The annual value for the last decade approximated $500,000; in 1900 it was $670,000. Virginia is one of the important mineral-water States; the product of 39 springs aggregated $320,000 in value in 1899. Gold, silver, and some other minerals have been mined for a long time, but are at present of very little importance.
Fisheries. Virginia ranks close to Massachusetts, New York, New Jersey, and Maryland in the importance of sea fisheries. In 1897 there were 28,000 men employed in the industry, this being a decided increase over the beginning of the decade. There was also an increase in the total product, but the value ($3,179,000) was much less, owing to the decline in prices. About two-thirds of the total product represented oysters, and it was in these that the decrease in price was greatest. Among other varieties, shad, menhaden, clams, and alewives are most important, the first three showing an increase in value during the period 1890-1900.
Agriculture. The short mild winters and the long summers, with plentiful rains, are conducive to farming. The soil, however, is generally much inferior to the soils of the Mississippi Valley, and the yield per acre very much less. There is a great variation of soil in the different physical divisions. The region of greatest fertility is the Shenandoah Valley, while the Piedmont district, extending across the State in a southwesterly direction par-
