A GEOARCHAEOLOGICAL INVESTIGATION AT THOMAS JEFFERSON’S MONTICELLO: CORRELATING LAND USE STRATEGIES WITH LANDSCAPE DYNAMICS ON THE NORTH SLOPE OF MONTICELLO MOUNTAIN

During the late 18th century, many plantation owners in the Chesapeake region responded to shifts in trans-Atlantic agricultural markets by supplementing or entirely replacing tobacco culture with more diversified agricultural strategies based around wheat. Thomas Jefferson's Monticello Plantation, located in the Southwest Mountains on the western edge of Virginia’s Piedmont, offers a unique opportunity to investigate the historical ecological dynamics associated with this shift. Documentary evidence dates the transition to commercial wheat agriculture at Monticello to the 1790s. Ongoing geoarchaeological investigations on Monticello Mountain are providing uniquely systematic evidence about the shifting character of cultivation strategies and their ecological consequences. One area on the mountain that has received attention is associated with a 312-foot rock alignment along the north slope of Monticello Mountain in an area Jefferson referred to as the Ancient Field. The east end of the rock alignment abuts a perennial first-order stream that drains Jefferson’s “Paw Paw Valley.” Documentary and archaeological evidence indicate that this area was cultivated as early as the 1740s. In the immediate area near the stream and upslope of the rock alignment, the topography is relatively flat suggesting that the alignment functioned as a sediment trap. In order to investigate the ecological history of the Paw Paw Valley, a 3-foot by 5-foot trench was excavated to a depth of 5 feet immediately upslope of the rock alignment. A suite of soil samples was collected and subjected to granulometic, geochemical, pollen, phytolith, micromorphological and geomagnetic analyses. We use the data to evaluate the following hypotheses: 1) The alignment and much of the sediment behind it are contemporaneous with Jefferson. 2) The stratigraphic trends are best explained by a transition from an agricultural regime characterized by hoeing or shallow plowing, field rotation, and low erosion rates to one characterized by permanent fields, crop rotations and fertilizer, deep plowing, and high erosion rates. 3) The rock alignment was built to mitigate the effects of high erosion rates on drinking water sources. 4) The advent of wheat as a principle commercial crop is responsible for this change.