The purpose of the geologic disturbance study is to identify zones or areas of prior disturbance. Disturbance herein is defined as any natural or man-made disturbance of the soils, sediments and rocks that occur along the proposed flood control project corridor. Natural disturbances include: (1) erosion of the flood plain by the lateral channel migration of the West Branch and/or its tributary Bald Eagle Creek; (2) flood scouring of the TO (0 - 10 feet above the normal pool elevation at the Jay Street Bridge) and Ti (10 - 25 feet above the normal pool elevation at the Jay Street Bridge) terraces during bankfull discharge; (3) erosion by surface runoff, primarily during the winter and early spring; (4) mass-wasting along the valley slopes and along the scarp slope of the T1 terrace within the project area and (5) bioturbation of the soils in the study area by naturally occuring plants and animals. Man made disturbances include: (1) plowing and disking of the T1 terrace surface; (2) municipal, industrial and residential landfills; (3) subsurface utility lines (gas, water, sewage, electric etc.); (4) bridge abutments, tunnels and dams; (5) industrial, municipal and residential structures; (6) highway and road construction (including both paved and unpaved); (7) railroad grades, surface culverts and retaining walls; (8) boat launches and docks (primarily on the lower TO terrace); (9) wells, cisterns and septic tank fields; and (10) cemeteries.