ANTHRACITE COAL AS A PROXY FOR HUMAN IMPACT AND ENVIRONMENTAL CHANGE, MID-ATLANTIC U.S.A

Alluvial sediment from both the Susquehanna River and the Delaware River valley shows an "event horizon" in stratigraphic profiles that resulted from the mining and transport of anthracite coal. Intensive anthracite mining occurred from the early 19^th century onward in the “Wyoming Valley” downstream of the juncture of the Lackawanna with the Susquehanna River. Portions of this coal were transported east, using the Upper Delaware canal system, to New York City. In both the Susquehanna and Delaware drainages, sediment washed into the river from coal piles at the mines themselves as well as coal barges and railroads which transported the coal to market. Historical documents and maps record many of the anthropogenic changes to river reaches including slackwater pools and other canal features on both the Susquehanna and the Delaware. In independent research on the stratigraphy of the middle and upper reaches of both drainages, we have employed thin-section petrography environmental SEM to identify and image the anthracite sedimentary particles themselves. Particle size and geochemical analyses identify modes of transport and relate the anthropogenic sediment to changes in the river floodplain and soils mapped at the land surface. Anthracite found in sediment from both Delaware Bay and Chesapeake Bay can be used as a proxy for periods of greater riverine input and perhaps drought as well. The mining and introduction of anthracite sediment marks a change in boundary conditions, reduced vegetation cover from logging and increased sediment supply from mining. However, the response time of anthracite sediment delivery appears lagged as it has continues to be eroded and transported down to the present, even though the active mining essentially ended by 1980.