Backbone Mountain
       7 ½’ quadrangles: Davis, WV-MD
       Garrett County
       Private Property (see www.highpointers.org for updates)
       Ridge and Valley Province, Appalachian Mountains

Sedimentary
3,360 ft 1,024 m

Pottsville Sandstone near the summit.

View west from near the summit.

Bedrock: Pottsville Sandstone

Pennsylvanian

Massive, light gray conglomerate and thin-bedded, gray to white sandstone with thin coal seams and minor shale horizons (cyclothems). The disconformable contact with the underlying red shales and sandstones of the Mauch Chunk Formation lies within 100 meters west of the summit ridge, which represents part of the Catskill delta, deposited as sediments eroded from mountains formed by the Acadian Orogeny along the eastern margin of Laurentia. The still older Devonian Jennings marine shale is exposed in the valley to the west at Mountain Lake Park, in the center of the eroded crest of an anticline. All these rocks were folded in the late Paleozoic Alleghenian Orogeny into the long canoe-shaped anticlines and synclines typical of the Ridge and Valley Province.

Backbone Mountain is part of a long linear ridge held up by east-dipping resistant rocks on the east flank of an anticline. The ridge continues northeast 25 miles to the Savage River water gap, and from there the same geology continues northeast as Big Savage Mountain to the Pennsylvania border and beyond (see Pennsylvania highpoint Davis Mountain). One of the best exposed synclines in the Ridge and Valley Province can be seen on I-68 near Hancock, Maryland, at Sideling Hill: (See photo and description at http://www.mgs.md.gov/esic/features/sidel.html.)

Surficial Geology: South of the limit of Pleistocene glaciation

Soil Series: Stony rough land: local pockets of soil between numerous outcrops, not differentiated on the soil survey map.

Selected References:

• Clark, William B. and others, 1902, Garrett County.: Maryland Geological Survey.
• Stone, Kenneth M. and E.D. Matthews, 1974, Soil Survey of Garrett County, Maryland: U.S. Soil Conservation Service.

Other suggested sources of information:

• Glossary: http://www2.nature.nps.gov/geology/usgsnps/misc/glossaryAtoC.html
• Time scale: http://www.ucmp.berkeley.edu/help/timeform.html
• Maryland Geological Survey: http://www.mgs.md.gov/