Someone (maybe the PA Geological Survey) has a fascinating booklet on the influence of geology at Gettysburg. All the hills are underlain by hard igneous rock, while the lowlands are soft shale.
23 posted on 10/11/2008 12:34:50 PM PDT by hellbender
25 posted on 10/11/2008 12:43:20 PM PDT by SunkenCiv
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