Nature and History in the Potomac Country: From Hunter-Gatherers to the Age of Jefferson

CODA: Ahone‘s Legacy

Much has changed along the Potomac since Nicholas Cresswell made his escape from Alexandria in 1776. The changes range from the patently obvious (a population that has mushroomed into the millions and the rise of an automobilecentered economy, society, and culture) to the nearly invisible (such as radical changes in the prevalence of certain single-celled floating organisms beneath the water’s surface), and they are evident from one end of Potomac country to the other. Although the most visible changes date to the twentieth century, the transformation of the environment was already underway when Cresswell recorded his impressions of the region: thanks to the rise of grain and dairy farming, new farming techniques, the conversion of large swaths of forest to fields, population growth, and the growth of industry, by the 1770s humans were already causing far more extensive environmental changes along the Potomac and its tributaries than ever before, similar in kind (if not yet in scale) to the massive environmental changes of the nineteenth and twentieth centuries. The colonial tobacco planter’s long fallows, hoe agriculture, and small, unruly looking, and stump-filled fields had left much of the land covered with trees, herbs, and shrubs. In contrast, small, independent farmers in the Age of Jefferson were in the process of switching to plow agriculture, which more profoundly disturbed the soil, encouraged the stripping of all vegetation from the fields (including stumps), destroyed the root systems of perennial species (thus altering soil chemistry by starving out the microorganisms that live upon those roots), and encouraged crop rotations and short fallows instead of the older system of allowing old fields to return to forest in twenty-year-long fallows. By the 1820s commercial fertilizers made it possible to more continuously work each field, to put into production marginal soils, and to alter rotations to include fewer replenishing crops such as clover, grass, or turnips. Mechanized gristmills, reapers, and c o d a Ahone’s Legacy ., other machines introduced in the century after the Revolution made it possible for each individual farmer to keep more land under cultivation (even before the advent of tractors), while continued population growth put many more farmers in the field. As a result the proportion of land that had been cleared soared from well under 20 percent in the 1730s to nearly 50 percent a century later. Much of the new clearance was on steeper slopes (particularly in the Piedmont) that were prone to erosion. Forest habitat for all manner of creatures was much reduced, as was overall biodiversity. Sedimentation rates increased as much as fourfold, enough to leave once-bustling harbors silted up and landlocked. Increased runoff from plowing and deforestation also transformed life below the surface of Ahone’s waters. Waterborne nutrients and the tiny creatures that fed upon them thrived on the fertilizers and other organic matter contained in the runoff from farmers’ neatly cleared fields, causing the water’s oxygen content and clarity to plummet. Bottom-dwelling plants and animals either suffocated or were starved for light.At the same time, increasingly commercialized and mechanized harvests were stripping the lower Potomac and the adjoining Chesapeake Bay of oysters. Since oysters cleanse the water by drawing it over their gills and filtering it of sediments and other suspended materials, their depletion further contributed to the transformation of the estuary “from a system of mostly bottom dwellers to one dominated by floating and swimming organisms.”As late as 1870 there were still sufficient oysters to filter the entire Chesapeake Bay estuary clean in just one week, but now there are so few oysters that “it would take them almost a year to do the job.”1 Industry also contributed to the degradation of the environment. Iron furnaces and forges multiplied after the Revolution, and large swaths of forest were cleared in order to feed them. Investors bought up thousands of acres of timberland to support each charcoal-hungry furnace: at Neabsco Creek up to fifty slaves at a time worked cutting and burning wood on the five thousand acres that supported the furnace, and the Keep Triste Furnace, near the juncture of the Shenandoah and Potomac rivers, was fed by ten thousand acres of woodlands. This 1808 map notes the locations of towns, substantial farms, and other enterprises; this section, encompassing Frederick Town, Maryland (right side, just above center), shows the locations of grist- and merchant mills (marked with a...