In a 1994 CRM survey of the Bald Eagle Valley (Centre and Blair Cos., PA)
I dealt with some cold blast (charcoal) iron furnaces and some "charcoal
stains" from potential charcoal making mounds (ca. 1820-1860).  The
report -- "Phase I/II Historical Archaeological Survey of the Proposed
U.S. Route 220 Transportation Improvement Project" by David S. Rotenstein
and Charlane Gross -- may be obtained from CHRS, Inc., North Wales, Pa.
I no longer work there and the address is not handy, but the phone number
is (215) 699-8006.
 
 
DSR