from John R. Stilgoe, Common Landscape of America, 1580-1845 [E169.1 .S85 1982]: Landscape is a slippery word. It means more than scenery painting, a pleasant rural vista, or ornamental planting around a country house. It means shaped land, land modified for permanent human occupation, for dwelling, agriculture, manufacturing, government, worship, and for pleasure. A landscape happens not by chance but by contrivance, by premeditation, by design; a forest or swamp or prairie no more constitutes a landscape than does a chain of mountains. Such land forms are only wilderness, the chaos from which landscapes are created by men intent on ordering and shaping space for their own ends. But landscapes always display a fragile equilibrium between natural and human force; terrain and vegetation are moulded, not dominated... (p 3)

Though this doesn't have a lot to do with the Valley of Virginia, it's pretty enlightening:

May 20, 1785, is a momentous date in United States history. On that day Congress authorized the surveying of the western territories (the 'backland', as the Congressmen called them during the lengthy debates) into six-mile-square townships. Each township, Congress directed, would be bounded by lines running due north-south and east-west; other parallel lines would divide each township into thirty-six square sections of 640 acres each...(p 99)

A simple but brilliant surveying innovation popularized squares in every colony, although only late in the 18th century. Edmund Gunter, an English surveyor who dies in 1626, invented an promoted "Gunter's chain", a surveying chain of 100 links of 0.66 feet each. The chain is therefore 22 yards long, and if an acre is described as 10 square chains, 640 acres fit precisely into a square mile of ground. No mathematical ratio is more important in the American Enlightenment landscape. (p 100)

Interesting summary of landscape effects of iron-making, p 290ff

Stilgoe cites John Brinckerhoff Jackson frequently