Re: Newbie questions: ( Surveying "virgin" creeks, home panning, suburban watersheds,etc.) Long Intro !

To address your mapping problem I would suggest you first study the
tectonics from the Grenville Formation at the core of the Appalachians
and then work eastward.  We now believe there may be numerous
subduction zones with associated volcanism distributed in the Piedmont
and Coastal Plain.  The break up of Pangea works into this problem
also.  There are some people doing this now. Try a search on Grenville
and you may discover current effort.