Cores collected from recent drilling in western Cape Cod, Massachusetts provide insight into the topography and petrology of the underlying bedrock. Cores from 64 drill sites spread over a approximately 140 km2 study area produced samples of granitoids (31), orthogneisses (20), basalts/diabases (4), amphibolites (3), felsic mylonites (2), and dolomitic rock (2). Granitoid composition ranges from granite to tonalite and quartz diorite, but it is dominated by two-feldspar granites. Hydrothermal alteration ...