Digital Bedrock Geologic Map of Saugus Iron Works National Historic Site and Vicinity, Massachusetts (NPS, GRD, GRI, SAIR, SAIR digital map) adapted from a Massachusetts Geological Survey Preliminary Report map by Kopera (2011). National Park Service (NPS) Geologic Resources Inventory (GRI) program. Geospatial Dataset-2176344. https://irma.nps.gov/Datastore/Reference/Profile/2176344 (Publication)