One resource so influential that it often shapes the economic pattern of a state is soil. Virginia is fortunate in having numerous types of soil: rich, black loam; light, sandy loam; clay and sand loam; limestone and clay soils. Most of these soils are easily adaptable to cultivation, and the use of crop rotation and of marl (a soil neutralizer) has fostered extensive production. Forests constitute approximately three-fifths or 60% of Virginia's total land area. There are many hardwood and softwood varieties in Virginia. The term, "hardwood," is sometimes a misleading one because a few of the so-called "softwood" trees are actually hard in substance. Hardwood trees shed their leaves annually, and they are called deciduous trees. Since softwood trees bear cones, they are called coniferous trees. The southern or yellow pine is the leading softwood or coniferous tree which thrives in Virginia because of the sandy soil of the coastal plain. Other softwoods are red spruce, hemlock, red cedar and cypress. Hardwoods include oak, chestnut, locust, hickory, walnut, gum, white ash, magnolia and dogwood. Although the forests are scattered throughout the state, the Tidewater, Piedmont and western portions of the state have the largest forested area. Fish are plentiful in Virginia because of the Atlantic Ocean, the Chesapeake Bay and the numerous rivers and mountain streams. Virginia usually ranks annually among the first ten states in the value of its fisheries. The principal fish are oysters and clams in Chesapeake Bay, blue crabs and shrimp in the Tidewater area, scallops in seacoast inlets, bads, bream, perch, pike, carp, catfish in inland waters and speckled and rainbow trout in mountain streams. Menhaden fish, found near the surface of the water, are inedible but are now being used for making fertilizer and oil in Virginia. The amount of waterpower is above average in Virginia due to many swift streams and rivers and the high elevation. This resource combined with an ample supply of steam coal has resulted in the production of electric power in Virginia at a much cheaper rate than in many other states. Furthermore, it is estimated that Virginia industry at the present time is using only approximately 10 per cent of its available waterpower supply. With respect to minerals, approximately one hundred and fifty kinds have been found in Virginia, and approximately forty have been mined and quarried recently. However, Virginia ranks nineteenth in United States mineral production and provides approximately 1.25% of the total United States mineral value.