Piedmont and Blue Ridge Crystalline rocks with glacial cover
Piedmont Chimney rock Blue Ridge Province
flow through fractures
Transition Fractured metamorphic and igneous rock Saprolite
Gneiss, schist bedrock Granite or other intrusive bedrock Distinct transition Gradational transition
Storage and transmission properties High porosity S y ? porosity Low storage cm/s
Saprolite sampled at different depths. Measure density and chemical composition. S.G. decreases from 2.1 in rock to 1.6 in shallow saprolite. S.G. decreases as minerals are altered and mass is removed. 0.5 gm/cc removed during weathering. Chemical concentrations indicate S.G. change largely due to weathering of feldspar to kaolinite as a two-stage reaction.
Saprolite thickness Typically 50 ft, but variable ft w.t ft bgs Frx zones in valleys Flat-lying frx
Saprolite thickness Greatest over valley or highland? Could be either
Ground watersheds
Lineaments
Specific capacity
Effects of lineaments on well yields in the Piedmont Other effects of location on well yield Factor of 2 to 7 difference in yield Factors from 3 to 25 between valley and hill
Well yields in different rock types and regions in the Piedmont gpm typical Roughly 20 gpm
Effects of well depth and diameter on yield in the Piedmont. Based on Daniels
Glaciated crystalline rocks in northern Appalachians
Other Hydrogeologic Settings in the Piedmont
Stockton Fm. Lockatong Fm. Passaic Fm. Orange Mt. Basalt Feltville Fm. Preakness Basalt Towaco Fm. Hook Mt. Basalt Boonton Fm. Conglomerates Palisade sill
Newark Basin, NJ Mesozoic Basins Sandstone aquifers Shale confining units Redbeds in the Hartford Basin, Conn Conglomerate Basalt Arkose
Carbonate rock aquifers
Water quality in Crystalline Rock aquifers
Crystalline rock Triassic Basin Carbonate rock meq/L
Crystalline Rock Triassic Basins Carbonate Aquifers
SC, GA, Al =100 mgpd