Brush Mountain is a

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...

ridge in the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

of central

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

, United States, lying east of the

Allegheny Front The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia, USA. The Allegheny Front forms the boundary between the ...

and west of

Tussey Mountain Tussey Mountain is a stratigraphic ridge in central Pennsylvania, United States, trending east of the Bald Eagle, Brush, Dunning and Evitts Mountain ridges. Its southern foot just crosses the Mason–Dixon line near Flintstone, Maryland, run ...

. It runs along the southeast side of the

Little Juniata River The Little Juniata River, sometimes called the "Little J," is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 8, 2011 tributary of the Juniata River in the Susquehanna River wa ...

and forms a horseshoe around

Sinking Run Sinking may refer to: * Sinking of a ship; see shipwrecking * Being underwater, submerged * Sinking (album), ''Sinking'' (album), a 1996 studio album by The Aloof * Sinking (behavior), the act of pouring out champagne in the sink * Sinking (metalw ...

, and is the westernmost ridge in its section of the

Ridge-and-valley Appalachians The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

. The western ridge line separates the

Logan Valley Antis Township is a township in Blair County, Pennsylvania, United States. The population was 6,499 at the 2010 census. History The township was named for Frederick Antes, a colonel who fought during the Revolutionary War. Geography Antis Townsh ...

from the Sinking Valley. Brush Mountain lies entirely in Blair County. It runs from the

water gap A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a prac ...

formed with

Bald Eagle Mountain Bald Eagle Mountain – once known locally as Muncy Mountain – is a stratigraphic ridge in the Ridge-and-Valley Appalachians of central Pennsylvania, United States, running east of the Allegheny Front and northwest of Mount Nittany. It lies al ...

by the

at Tyrone, south to the Sinking Valley

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

fold near Altoona then turns northeast to the Canoe Valley syncline fold, where the ridge becomes

Canoe Mountain Canoe Mountain is a stratigraphic ridge in central Pennsylvania, United States, running east of the Allegheny Front and west of Tussey Mountain. It forms a continuous ridge with Brush Mountain to the west. To the south, across the water gap fo ...

. The total length of Brush Mountain is approximately . No major roads or rivers cross the ridge or run through gaps. Kettle Reservoir collects surface runoff from a small area in the fold, and the dam was made by filling in a small ravine. Kettle Road, a secondary road, runs through the ravine near the dam east into Sinking Valley. A major power transmission line crosses the ridge twice, midway between the folds. The Brush Mountain Ridge is popular with

soaring bird This is a list of soaring birds, which are birds that can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by means of a specialized tendon. ;Bird of prey * Buzzards * ...

s and

glider Glider may refer to: Aircraft and transport Aircraft * Glider (aircraft), heavier-than-air aircraft primarily intended for unpowered flight ** Glider (sailplane), a rigid-winged glider aircraft with an undercarriage, used in the sport of glidin ...

pilots ridge soaring along its slopes. This ridge is part of a chain of ridges that stretch south to

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

. The fold at the south end of Brush Mountain forms a gap in the chain, with the continuation of the ridge line south on

Dunning Mountain Dunning Mountain is a stratigraphic ridge in central Pennsylvania, United States. The mountain's north end is at McKee Gap, which separates it from Short Mountain, and where Halter Creek flows westward towards the Frankstown Branch of the Juni ...

Pennsylvania State Game Lands The Pennsylvania State Game Lands (SGL) are lands managed by the Pennsylvania Game Commission (PGC) for hunting, trapping, and fishing. These lands, often not usable for farming or development, are donated to the PGC or purchased by the PGC with hun ...

Number 166 lies on Brush Mountain south of Sinking Hollow and on Canoe Mountain and in the valley between.Pennsylvania State Game Lands Number 166
retrieved 14 November 2018

Tornado

Shortly after 11:00 a.m. EST on July 19, 1996, an F1 tornado touched down northeast of Altoona approximately 1 mile northwest of Sickles Corner on Brush Mountain. This tornado moved southeast, taking down a swath of trees along the mountain and causing minor damage to homes along a path before ending one half mile southeast of Sickles Corner. The path width averaged about one half mile wide. This storm was the fourth in the family of tornadoes that had crossed

Clarion Clarion may refer to: Music * Clarion (instrument), a type of trumpet used in the Middle Ages * The register of a clarinet that ranges from B4 to C6 * A trumpet organ stop that usually plays an octave above unison pitch * "Clarion" (song), a 2 ...

Jefferson Jefferson may refer to: Names * Jefferson (surname) * Jefferson (given name) People * Thomas Jefferson (1743–1826), third president of the United States * Jefferson (footballer, born 1970), full name Jefferson Tomaz de Souza, Brazilian foo ...

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

, Clearfield and

Cambria Cambria is a name for Wales, being the Latinised form of the Welsh name for the country, . The term was not in use during the Roman period (when Wales had not come into existence as a distinct entity). It emerged later, in the medieval period, ...

counties.

Geology

Brush Mountain is in the northern portion of the

Ridge and Valley The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

province of the vast

range.

and neighboring

are made up of

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

rocks, consisting of the

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

Bald Eagle Formation The Ordovician Bald Eagle Formation is a mapped bedrock unit in central Pennsylvania, USA. It is a ridge-forming unit in the Appalachian Mountains. Description The Bald Eagle is defined as a gray to olive-gray and grayish-red, fine to coarse-gra ...

(

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

), the

Juniata Formation 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 ...

( shale and siltstone), and the Silurian

Tuscarora Formation 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. Description The Tuscarora is a thin- to thick-bedded fine-gr ...

(

quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tec ...

) that were folded during the

Alleghanian orogeny The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 1957 ...

in the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

period, then eroded down to their present form.Berg, Thomas M., and Dodge, Christine M., eds., Map 61, ''Atlas of Preliminary Geologic Quadrangle Maps of Pennsylvania''. Bureau of Topographic and Geologic Survey, 1981
Millheim QuadrangleSpruce Creek Quadrangle
The Tuscarora Quartzite is more resistant to erosion than the Bald Eagle Sandstone, and both are more resistant than the Juniata formation between them or the other formations stratigraphically above and below them. The two sandstones thus form a double ridge line, with the harder Tuscarora at the crest. On the north end of the mountain, the rock layers are tipped near vertical, and the mountain has the same double-crested ridge shape as the Bald Eagle ridge extending to the north, with the crests near the center of the harder rock layers. A little further south, there are several fault lines running across the ridge, and the rock layers then slope down to the west. This leaves the Tuscarora formation more parallel to the steeper western slope, with the crest marking the dividing line between the layers. The tougher rock also protected the slope from erosion, leaving a higher southern ridge line. The tilted aspect of the rock layers leaves the Juniata formation more perpendicular to the upper portion of the shallower opposite slope, below the steep crest. The Bald Eagle formation below holds back the eroding rock, creating a shelf above a steeper lower slope running down to Sinking Valley. The drainage in the shelf area cut a series of small ravines, leaving terraces between them. The terraces wrap around the inside of the

fold around Sinking Valley, and then around the outside of the reverse fold on

References

{{Mountains of Pennsylvania Ridges of Pennsylvania Ridges of Blair County, Pennsylvania Allegheny Mountains

Tornado

Geology

See also

References