sentences:  The cities of Wilmington and Newark lie at the Fall Line, where the northern margin of the younger Cretaceous coastal plain sediments overlie the older Piedmont rocks.The Delaware Geological Survey is the primary source of information about Delaware geology and hydrogeology, such as surface and sub-surface geologic rock formations, extent and quality of aquifers, stream and groundwater monitoring, water supply, earthquakes, floods and droughts, coastal processes (tides, beach erosion), topographic mapping, state mapping and GIS coordination.DGS research and service activities are focused on five areas