GEOLOGIC FRAMEWORK FOR EVALUATING GROUND WATER RESOURCES IN THE SOUTHERN WORCESTER MOUNTAINS, CENTRAL VERMONT
The Worcester Mts are the dominant topographic feature in the study area - a NNE trending, south-plunging anticlinorial ridge cored by resistant schists; this lithology forms the steepest slopes. The flanks and surrounding valleys are composed of generally less resistant amphibolite, phyllites, and granofels. Based on photolineament and structural analysis, the overall topographic grain is parallel to ductile structures, however, specific domains in quartz-rich lithologies are dominated by fractures orthogonal to ductile structures. Drainage patterns in recharge areas are fracture controlled.
Surficial deposits include till, esker and other ice-contact deposits, lacustrine deposits ranging from silty clay to pebbly sand, alluvial fans and fan-terraces, stream terraces, and alluvium. Former lake shorelines range in elevation from 1230 feet down to 650 feet. An esker buried under lake deposits in the Winooski River valley bottom may be an important aquifer. Relatively impermeable ice contact and lacustrine deposits that directly overlie bedrock may serve as aquitards to locally reduce bedrock aquifer recharge and produce artesian conditions in nearby bedrock wells.
Our analyses seek to identify the relationship(s) between well yield and l) lithologic and surficial units 2) proximity to topographic lineaments, 3) surficial material thickness and permeability, 4) surface water proximity, 5) major bedrock structures, 6) slope and other topographic indices, 7) drainage area size.