New Hampshire

Mt. Washington (Agiocochook)
       7 ½’ quadrangle: Mt. Washington, NH
       Coos County
       White Mountain National Forest
       Appalachian Trail
       Presidential Range, White Mountains

Metamorphic
6,288 ft (1,917 m)


Mt. Washington summit from Lakes of the Clouds, looking northeast. Note puff of smoke from cog railway on left skyline. (PTJ, 1990)


Rock core from water well for Appalachian
Mountain Club hut at Lakes of the Clouds. Shows
alternating quartzite and schist typical of the Littleton
Formation. (PJT, 2004)

Bedrock: Littleton Formation

Devonian

Gray, coarse-grained quartz-muscovite-biotite-staurolite-sillimanite-garnet-feldspar schist and lighter gray quartzite. Huntington Ravine member at the summit: thin, evenly bedded schist and quartzite, folded and refolded in a complicated pattern during the Acadian orogeny. Graded beds are commonly preserved, although metamorphic minerals in the schist (metamorphosed shales) are coarser than in the quartzites (metamorphosed sandstone layers), opposite from what the grain sizes would have been prior to metamorphism. Large pseudomorphs of sillimanite after andalusite are a distinctive feature; locally pinkish andalusite is still present, and in other areas the sillimanite has been subsequently replaced by micas.

Surficial Geology: Many parts of the summit are covered by felsenmeer, a litter of frost-fractured rocks, mostly locally derived, but including igneous erratics, which prove that the summit was entirely overridden by glaciers. Several shoulders of the mountain, for example Bigelow Lawn south of the summit, show nice examples of patterned ground. Tuckerman’s Ravine, Huntington’s Ravine and the Great Gulf are excellent examples of cirques. Some glacial geologists have argued that the cirques were formed by local valley glaciers following continental glaciation, but most now agree that the cirques predate the advance and ablation of the Wisconsinan continental ice sheet about 14,000 years BP.

Additional Photos:


Mt. Washington from Pinkham Notch, looking northwest
toward Tuckerman's Ravine. (PJT, 1978)


Bigelow Lawn near the head of Tuckerman's Ravine. Lion's
Head middle right, Carter Range in distance. (PJT, 1990)

Selected References:

  • Billings, Marland P., 1941, "Structure and metamorphism in the Mt.Washington area, New Hampshire": Geological Society of America Bulletin v.52, p.863-936.
  • Billings, M.P., K.S. Fowler-Billings, C.A. Chapman, R.W. Chapman and R.P. Goldthwaite, 1946, Geology of the Mt. Washington quadrangle, New Hampshire: NH State Planning and Development Commission, scale 1:62,500.
  • Davis, P.T., B.K.Fowler, D.J.Thompson and W.B.Thompson, 1996, "Continental and alpine glacial sequence and mass wasting on Mt. Washington, northern New Hampshire": Trip A4, p.79-116 in Van Baalen, M.R., editor, Guidebook to Field Trips in Northern New Hampshire and Adjacent Regions of Maine and Vermont, New England Intercollegiate Geological Conference, 88th Annual Meeting, Dept. of Earth & Planetary Sciences, Harvard University, Cambridge, MA.
  • Eusden, J.Dykstra. and students, 1996, "Bedrock Geology of the Presidential Range, New Hampshire": Trip A3, p.59-78 in Van Baalen, M.R., editor, Guidebook to field trips in northern New Hampshire and adjacent regions of Maine and Vermont, New England Intercollegiate Geological Conference, 88th Annual Meeting, Dept. of Earth & Planetary Sciences, Harvard University, Cambridge, MA.

Other suggested sources of information:


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