1. Total-field aeromagnetic map of portions of Penobscot, Piscataquis, and Aroostook counties, Maine [microform] Yale Public content 1993. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; Books and Open-File Reports Section, distributor. English. Public. Maine, Aroostook County, Penobscot County, and Piscataquis County.