Abstract
The Merrymeeting Lake area, like several other small areas in central New Hampshire, has a considerable variety of igneous rocks grouped together. Rock types include, from oldest to youngest, leucorhyolite, diorite-gabbro, granodiorite, granite, granite porphyry, and several dike rocks.
The leucorhyolite may be extrusive, but the other rocks are intrusive. The intrusions cut sharply across the foliation and contacts of the older rocks. They are mainly round or oval in ground-plan. Field relations indicate the cauldron subsidence method of intrusion, which is the same as that in near-by areas.
Evidence supports the correlation of these rocks with the White Mountain magma series of possible Carboniferous age.
The variety of rock types indicates considerable magmatic differentiation. Similarity to other areas of White Mountain magma series probably indicates similar differentiation.
