DETAILED BEDROCK MAPPING OF THE DEVONIAN LITTLETON FORMATION, MT. MADISON, PRESIDENTIAL RANGE, NEW HAMPSHIRE

To better understand the complex tectonic history of the Acadian orogeny in the Presidential Range, New Hampshire, the bedrock geology of the alpine zone surrounding Mt. Madison was mapped at a scale of circa 1:3,000. The Presidential Range lies within the belt of Silurian and Devonian metasedimentary rocks that compose Central Maine Terrane. The well-exposed, higher elevations of the Presidential Range are dominated by the Littleton Formation, which has been complexly deformed and metamorphosed. A new bedrock geologic map and cross-section along a transect from Madison Springs Hut to treeline on Osgood Ridge was constructed to redefine the lithologies and geologic contacts. Three new and six total members of the Devonian Littleton Formation have been defined by variations in bedding style and the ratio of schist to quartzite. A prominent sedimentary facies change has been mapped between two of these members. D1 deformation is characterized by an overall inverted limb with two meso-scale, east-facing, north-plunging F1 folds with hinge-parallel L1 pseudoandalusite lineations. A total of six gently plunging, D4 antiformal synclines and synformal anticlines with west-dipping S4 axial surfaces have been identified in the study area. Stereo- and orthographic projections were used to construct the revised map, which will be incorporated into an updated version of the bedrock geologic map of the entire Presidential Range.