Hatcher Pass is a mountain pass through the southwest part of the Talkeetna Mountains, Alaska. It is named after Robert Hatcher, a prospector and miner. The nearest cities are Palmer and Wasilla approximately 12 miles (19 km) to the south, and Willow approximately 26 mi (42 km) to the west. The communities are at an elevation of approximately 250 ft (76 m) in the Mat-Su valley.
The Chilhowee Group is a sedimentary body composed of early Cambrian siliciclastic sedimentary rocks which crop out along the eastern margin of the Blue Ridge province in Alabama, Maryland, Tennessee, North Carolina, Virginia, and West Virginia. They represent a rift to passive margin sequence, with mostly coarse, feldspathic sandstones and conglomerates in the lower member and shales and phyllite in the upper members. The Chilhowee Group contains four formations; the Loudoun Formation, Weverton Formation, Harpers Formation and Antietam Formation. Another name for the Harpers formations is the Hampton formation, and the Antietam Formation is also known as the Erwin Formation. The Hampton Formation has minor economic importance in the area near the James River Face Wilderness. As of 1982 there were three quarries operating near the James River Face Wilderness. Those quarries produced roofing shale, light weight aggregate, and various materials for brick making. The Antietam Formation also had a minor economic importance, particularly from 1945 up until 1966. There were three quarries producing crushed quartzite, which was used to produce concrete aggregates, road metal and railroad ballast.
The Silurian Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia, USA.
The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.
The Ordovician Reedsville Formation is a mapped surficial bedrock unit in Pennsylvania, Maryland, Virginia, West Virginia, and Tennessee, that extends into the subsurface of Ohio. This rock is a slope-former adjacent to the prominent ridge-forming Bald Eagle sandstone unit in the Appalachian Mountains. It is often abbreviated Or on geologic maps.
Wills Creek Formation is a mapped Silurian bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
The Hamilton Group is a Devonian-age geological group in the Appalachian region of the United States. It is present in New York, Pennsylvania, Maryland, Ohio, West Virginia, northwestern Virginia and Ontario, Canada. It is mainly composed of marine shale with some sandstone. There are two main formations encompassed by the group: the Mahantango Formation and the Marcellus Shale. In southwestern Virginia, where the two sub-units are not easily distinguishable, the Hamilton Group is broadly equivalent to the Millboro Shale or Millboro Formation. The group is named for the village of Hamilton, New York. These rocks are the oldest strata of the Devonian gas shale sequence.
The Devonian Mahantango Formation is a mapped bedrock unit in Pennsylvania, West Virginia, and Maryland. It is named for the North branch of the Mahantango Creek in Perry and Juniata counties in Pennsylvania. It is a member of the Hamilton Group, along with the underlying the Marcellus Formation Shale. South of Tuscarora Mountain in south central Pennsylvania, the lower members of this unit were also mapped as the Montebello Formation. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database.
The Mississippian Pocono Formation is a mapped bedrock unit in Pennsylvania, Maryland, and West Virginia, in the United States. It is also known as the Pocono Group in Maryland and West Virginia, and the upper part of the Pocono Formation is sometimes called the Burgoon Formation or Burgoon Sandstone in Pennsylvania. The Pocono is a major ridge-former In the Ridge-and-Valley Appalachians of the eastern United States
The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, Ohio, and Alabama. It is a major ridge-former in the Ridge-and-Valley Appalachians of the eastern United States. The Pottsville Formation is conspicuous at many sites along the Allegheny Front, the eastern escarpment of the Allegheny or Appalachian Plateau.
The Devonian Old Port Formation is a mapped bedrock unit in Pennsylvania, USA. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. Current nomenclature usage by U.S. Geological Survey restricts the name Old Port Formation to Pennsylvania, but correlative units are present in adjacent states.
The Devonian Foreknobs Formation is a mapped bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
The island of Taiwan was formed approximately 4 to 5 million years ago at a convergent boundary between the Philippine Sea Plate and the Eurasian Plate. In a boundary running the length of the island and continuing southwards, the Eurasian Plate is sliding under the Philippine Sea Plate. In the northeast of the island, the Philippine Sea Plate slides under the Eurasian Plate. Most of the island comprises a huge fault block tilted to the west.
The Ridgeley sandstone is a sandstone or quartzite of Devonian age found in the Appalachian Mountains of Pennsylvania, Maryland, West Virginia, and Virginia, United States. The Ridgeley is fine-grained, siliceous, calcareous in its lower strata, sometimes fossiliferous, and sometimes locally pebbly or conglomeritic. Varying in thickness from 12 to 500 feet, this rock slowly erodes into white quartz sand that often washes or blows away, but sometimes accumulates at large outcrops. When freshly broken, the rock is white, but outcrop surfaces are often stained yellowish by iron oxides.
The Oriskany Sandstone is a Middle Devonian age unit of sedimentary rock found in eastern North America. The type locality of the unit is located at Oriskany Falls in New York. The Oriskany Sandstone extends throughout much of the Appalachian Basin.
The Williamsport Sandstone is a sandstone geologic formation in West Virginia, Virginia, Pennsylvania, and Maryland. the formation includes the Cedar Creek Limestone member. Near Cumberland, Maryland it includes the Cedar Creek Limestone member. It preserves fossils dating back to the Silurian period.
The Tomstown Dolomite or Tomstown Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating to the Cambrian Period.
The Harpers Formation is a geologic formation in Maryland, Pennsylvania, Virginia, and West Virginia, consisting of schist, phyllite, and shale. It dates back to the early Cambrian period. It is considered part of the Chilhowee Group.
The Waynesboro Formation is a limestone, dolomite, and sandstone geologic formation in Virginia, Maryland, Pennsylvania and West Virginia. In some areas it is composed of limestone and dolomite. The Waynsboro Formation is one of the formations that make up the Shenandoah Valley. It dates back to the Cambrian period and is not considered fossiliferous.
The Ashe Metamorphic Suite, also referred to as the Ashe Formation, was named after its type locality, Ashe County, North Carolina. The Ashe Metamorphic Suite is located in the Eastern Blue Ridge providence that extends from North Carolina up to South-Western Virginia. It is a collection of metamorphic rocks of both sedimentary and volcanic origin. Zircon dating indicates an age of 470 to 335 Ma for the unit. The protolith of the Ashe Metamorphic Suite was deposited during the Late Proterozoic and reaching its cooling age during the end of the Devonian. The Ashe Metamorphic Suite is overwhelmingly composed of amphibolites and mica schists.
Tight folds in the schist of Antietam Formation
Thin section of schist. Porphyroblastic biotite, a, in a dolomitic matrix. The tourmaline, t, is epigenetic.
