Bedrock Geologic Map of the Hubbard Brook Experimental Forest, Grafton County, New Hampshire, USGS/OFR 00-45

Our mapping study was funded by the USGS Toxic Substances Hydrology Program and was undertaken for the following reasons: 1) to ascertain whether the area might have a greater number of mappable lithologic units than shown on Barton's (1997) map, and to verify the stratigraphically higher formations shown on the map; 2) to have sufficient data to draw geologic cross- sections through the Mirror Lake research site; 3) to gather more data on brittle fracture distribution and orientation; and 4) to assess the degree to which the subsurface lithologies, ductile structures, and fractures observed at the two Mirror Lake well fields correlate with the geology of the surrounding region.

The bedrock geology of the Hubbard Brook Experimental Forest, Grafton County, New Hampshire is described in this report of new field investigation. The database includes contacts of bedrock geologic units, faults, folds, and other structural geologic information, as well as the base maps on which the mapped geological features are registered. This report supersedes Barton (1997).