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Today in Shenandoah National Park, the rocks of the Chilhowee Group form steep ridges and hollows that are covered in eroded rock debris called talus. These rocks have experienced weathering which has created soil able to support vegetation.
Oct 26, 2023 · In the valleys and ridges to the west, thick sequences of limestone and other marine rocks preserve evidence for the rest of this underwater period. The ancient Grenville rocks, the lava flows, and the sediments represent the three main geologic units found within Shenandoah.
May 30, 2023 · Chilhowee metasedimentary rocks, from the shores of an ocean predating the Atlantic, now create the steep slopes and rugged topography of the park’s unique South District.
- U.S. Geological Survey
- Stonehenge Limestone
- Beekmantown Group
- Devonian and Silurian Rocks That Underlie Massanutten Mountain
- Introduction
- Acknowledgments
- DSu
- Sm
- Great Valley and Page Valley
- Beekmantown Group, undivided (Middle and Lower Ordovician)—Light-
- Conococheague Limestone (Lower Ordovician and Upper Cambrian)—
- chs
- Zrl
- Yog
- Orthopyroxene monzogranite-quartz monzodiorite (Mesoproterozoic)—
- Orthopyroxene granite-monzogranite (Mesoproterozoic)—Dark-gray,
- Ylg
- Orthopyroxene syenogranite and monzogranite gneiss (Mesoproterozoic)—
U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey
The Lower Ordovician Stonehenge Limestone (Os) consists of silty, laminated limestone overlain by thick-bedded, fossiliferous limestone. The upper part consists of algal bioherms, intraformational conglomerates, and bioclastic beds that alternate with thin dolostone beds.
The Middle and Lower Ordovician Beekmantown Group (Ob) consists of the Stonehenge Limestone and its Stoufferstown Member, Rockdale Run Formation, and Pinesburg Station Dolomite, which are not differentiated on the geologic map (plate 1). The basal part of the Stonehenge Limestone (the Stoufferstown Member) consists of silty, laminated limestone, wh...
The rocks that overlie the Martinsburg Formation are resistant to erosion and underlie Massanutten Mountain in the Massanutten synclinorium. The Silurian Massanutten Sandstone (Sm) caps the ridges and consists of light-gray, fine- to coarse-grained, locally conglomeratic, cross-laminated sandstone. These rocks are overlain by a sequence of Silurian...
Deposits of unconsolidated surficial materials and the resulting landforms document the most recent part of the geologic history of the Shenandoah National Park region. The surficial materials contribute to the different types of soil, associated flora and fauna, and land use. Some of the landforms and deposits reflect millions of years of processe...
This research was funded by the U.S. Geological Survey’s National Cooperative Geologic Mapping Program’s Federal Mapping Component (FEDMAP) and University Geologic Mapping Component (EDMAP). Significant contributions were made by student research assistants from George Washington University and the College of William and Mary, who were supported by...
Devonian and Silurian rocks, undivided—Includes the formations listed below Mahantango Formation (Middle Devonian)—Gray mudstone, sandstone, and fossiliferous shale Needmore Shale (Middle and Lower Devonian)—Greenish-gray, fossiliferous shale and calcareous mudstone; black shale at the base Tioga Ash Bed (Middle and Lower Devonian)—Gray shale and s...
Bloomsburg Formation (Upper Silurian)—Red mudstone interbedded with red, ferruginous sandstone and shale McKenzie Formation (Upper and Middle Silurian)—Gray, calcareous shale Massanutten Sandstone (Silurian)—Light-gray, fine- to coarse-grained, cross laminated, locally conglomeratic sandstone
Om Oeln Ob Os Oc e wa Martinsburg Formation (Upper and Middle Ordovician)—Light-brown shale, calcareous shale, and siltstone. Contains thin to medium beds of sandstone and metagraywacke in the upper part; gray, argillaceous limestone at the base Edinburg Formation, Lincolnshire Limestone, and New Market Limestone, undivided (Middle Ordovician)—G...
gray, medium- to thick-bedded dolostone and laminated dolostone containing white and light-gray chert nodules. Weathered surface characterized by “butcher-block” of cross-hatched joints. Irregular bedding at top is due to collapse breccia and paleokarst Stonehenge Limestone (Lower Ordovician)—Dark-gray, fine- to medium-grained, thick-bedded, fossil...
Light-gray, calcareous to dolomitic sandstone; medium-gray, fine-grained limestone with intraformational conglomerate; and light-gray, fine-grained dolostone interbedded with dark- to light-gray, laminated, algal limestone; dolomitic limestone; and light-brown dolostone and calcareous sandstone Elbrook Limestone (Upper and Middle Cambrian)—Medium-g...
cw Antietam Formation (Lower Cambrian)—Light-olive- to olive-gray, medium- to coarse-grained, medium-bedded, locally ferruginous, micaceous, silty metasandstone interbedded with very fine grained, silty metasandstone to sandy metasiltstone. Local ferruginous horizons with abundant botryoidal hematite and limonite are located near contact with over...
Amissville Alkali Feldspar Granite—Gray, medium-grained alkali feldspar granite composed of mesoperthite, quartz, and diagnostic quartz phenocrysts. Small, irregular (miarolitic) cavities contain protruding quartz crystals Battle Mountain Alkali Feldspar Granite—Gray, medium-grained alkali-feldspar granite composed of alkali-feldspar-dominant mesop...
Arrington Mountain Alkali Feldspar Granite—Gray, medium-grained, equigranular alkali-feldspar granite composed of mesoperthite (chiefly microcline), quartz, and hastingsite, biotite, fluorite, and rare garnet and muscovite Rivanna Granite—White, medium-grained, and equigranular granite composed of quartz, plagioclase, and alkali-feldspar-dominant m...
Dark-green to black, medium- to coarse-grained, inequigranular, massive and nonfoliated, orthopyroxene-, amphibole-, and clinopyroxene-bearing orthopyroxene monzogranite and quartz monzodiorite Megacrystic quartz monzonite (Mesoproterozoic)—Light- to medium-gray, medium-grained to megacrystic, weakly foliated quartz monzonite containing porphyrobla...
medium- to coarse-grained, equigranular, weakly to strongly foliated, Yfh Yll Yomg Yos Ygd Yoq Yon Yod Ypg
orthopyroxene-, amphibole-, biotite-, and garnet-bearing orthopyroxene granite-monzogranite Flint Hill Gneiss (Mesoproterozoic)—Dark- to medium-gray, medium-grained, inequigranular, strongly foliated, locally migmatitic quartzofeldspathic syenogranite to monzogranite in compositional layers separated by biotite. Includes gray and blue quartz grains...
Gray, medium- to coarse-grained, compositionally layered, strongly foliated orthopyroxene-, biotite-, garnet-, and clinopyroxene-bearing orthopyroxene syenogranite and monzogranite gneiss. Exhibits transposed garnetiferous leucocratic layers Orthopyroxene granodiorite gneiss (Mesoproterozoic)—Dark-gray, medium- to coarse-grained, compositionally la...
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Molten magma, miles beneath the earth's surface, slowly solidified to become the "basement rock," or core, of what we know today as the Blue Ridge Mountains. For the next 500 million years, erosion and the uplifting of the earth's crust exposed the granitic basement rock.
Some common metamorphic rocks found in the park include gneiss, schist, and slate. Sedimentary Rocks. Sedimentary rocks can also be found in Shenandoah National Park, particularly in areas where ancient seas once covered the land.
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Nov 28, 2007 · Much of the history of these processes and of the resultant mountains can be found in the Blue Ridge rocks. Some geologic processes and events can be documented with certainty, others are more obscure, and many we can only speculate about.
