Gap (landform)

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A zoomed in view of the image below showing the Location of Kittanning Gap, one of the gaps of the Allegheny, along a tributary of the Kittanning Run.
* The USGS GNIS systems placement of the location of Kittanning Gap, is along a tributary of the Kittanning Run, not in the notch formed by the main stream. The black trace in this map forming a hairpin turn above the Lakes is the famous & historic Horseshoe Curve built by the Pennsylvania Railroad which crosses over four different streams sitting in the bottom end of water gaps in the view, and finishes its climb in a fifth, seen below in the next (zoomed out) map, just north of a sixth Blair Gap, where the historical Allegheny Portage Railroad climbed the Allegheny escarpment heading west. USGS National Map viewer after GNIS finding Kittaning Gap, Pennsylbania near Altoona, PA and showing the PRR Horseshoe Curve.png
A zoomed in view of the image below showing the Location of Kittanning Gap, one of the gaps of the Allegheny, along a tributary of the Kittanning Run.
 The USGS GNIS systems placement of the location of Kittanning Gap, is along a tributary of the Kittanning Run, not in the notch formed by the main stream. The black trace in this map forming a hairpin turn above the Lakes is the famous & historic Horseshoe Curve built by the Pennsylvania Railroad which crosses over four different streams sitting in the bottom end of water gaps in the view, and finishes its climb in a fifth, seen below in the next (zoomed out) map, just north of a sixth Blair Gap, where the historical Allegheny Portage Railroad climbed the Allegheny escarpment heading west.

A gap is a geological formation that is a low point or opening between hills or mountains or in a ridge or mountain range. It may be called a col, notch, pass, saddle, water gap, or wind gap. Geomorphologically, a gap is most often carved by water erosion from a freshet, stream or a river. [1] Gaps created by freshets are often, if not normally, devoid of water through much of the year, their streams being dependent upon the meltwaters of a snow pack. Gaps sourced by small springs will generally have a small stream excepting perhaps during the most arid parts of the year.

Water gaps of necessity often cut entirely through a barrier range and riverine gaps may create canyons such as the riverine gaps of the Danube River, Lehigh River Gorge, the Colorado River's Grand Canyon and the Genesee River. Such cuttings may expose millennia of strata in the local rock column writing the geologic record.

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<span class="mw-page-title-main">Valley</span> Low area between hills, often with a river running through it

A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas.

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<span class="mw-page-title-main">Wasatch Range</span> Mountain range in Utah, United States

The Wasatch Range or Wasatch Mountains is a mountain range in the western United States that runs about 160 miles (260 km) from the Utah-Idaho border south to central Utah. It is the western edge of the greater Rocky Mountains, and the eastern edge of the Great Basin region. The northern extension of the Wasatch Range, the Bear River Mountains, extends just into Idaho, constituting all of the Wasatch Range in that state.

<span class="mw-page-title-main">Yampa River</span> River in Moffat and Routt counties in Colorado, United States

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<span class="mw-page-title-main">Dolores River</span> River in Colorado and Utah in the United States

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<span class="mw-page-title-main">Freshet</span>

The term freshet is most commonly used to describe a snowmelt, an annual high water event on rivers resulting from snow and river ice melting. A spring freshet can sometimes last several weeks on large river systems, resulting in significant inundation of flood plains as the snowpack melts in the river's watershed. Freshets can occur with differing strength and duration depending upon the depth of the snowpack and the local average rates of warming temperatures. Deeper snowpacks which melt quickly can result in more severe flooding. Late spring melts allow for faster flooding; this is because the relatively longer days and higher solar angle allow for average melting temperatures to be reached quickly, causing snow to melt rapidly. Snowpacks at higher altitudes and in mountainous areas remain cold and tend to melt over a longer period of time and thus do not contribute to major flooding. Serious flooding from southern freshets are more often related to rain storms of large tropical weather systems rolling in from the South Atlantic or Gulf of Mexico, to add their powerful heating capacity to lesser snow packs. Tropically induced rainfall influenced quick melts can also affect snow cover to latitudes as far north as southern Canada, so long as the generally colder air mass is not blocking northward movement of low pressure systems.

<span class="mw-page-title-main">U-shaped valley</span> Valleys formed by glacial scouring

U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight sides and a flat or rounded bottom. Glaciated valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring. When the ice recedes or thaws, the valley remains, often littered with small boulders that were transported within the ice, called glacial till or glacial erratic.

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<span class="mw-page-title-main">River</span> Natural flowing watercourse

A river is a natural flowing watercourse, usually a freshwater stream, flowing on the surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities, a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; the language is vague.

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<span class="mw-page-title-main">Course of the Colorado River</span> Route and confluences of the Colorado River in the United States and Mexico

The Colorado River is a major river of the western United States and northwest Mexico in North America. Its headwaters are in the Rocky Mountains where La Poudre Pass Lake is its source. Located in north central Colorado it flows southwest through the Colorado Plateau country of western Colorado, southeastern Utah and northwestern Arizona where it flows through the Grand Canyon. It turns south near Las Vegas, Nevada, forming the Arizona–Nevada border in Lake Mead and the Arizona–California border a few miles below Davis Dam between Laughlin, Nevada and Needles, California before entering Mexico in the Colorado Desert. Most of its waters are diverted into the Imperial Valley of Southern California. In Mexico its course forms the boundary between Sonora and Baja California before entering the Gulf of California. This article describes most of the major features along the river.

<span class="mw-page-title-main">Gaps of the Allegheny</span>

The gaps of the Allegheny, meaning gaps in the Allegheny Ridge in west-central Pennsylvania, is a series of escarpment eroding water gaps along the saddle between two higher barrier ridge-lines in the eastern face atop the Allegheny Ridge or Allegheny Front escarpment. The front extends south through Western Maryland and forms much of the border between Virginia and West Virginia, in part explaining the difference in cultures between those two post-Civil War states. While not totally impenetrable to daring and energetic travelers on foot, passing the front outside of the water gaps with even sure footed mules was nearly impossible without navigating terrain where climbing was necessary on slopes even burros would find extremely difficult.

References

Location of Kittanning Gap after GNIS finding of 'Kittanning Gap, Pennsylvania' seen in USGS National Map viewer screenshot. The gap is located effectively in a western suburb of Altoona, PA.
* The maps on this page also are showing the nearby PRR Horseshoe Curve which crosses three other gaps and the confluence of Kittanning Run with .
* The Kittanning Gap gives this 'choice way' of climbing the escarpment to wagons or mule trains on the way to the west side of the Allegheny Mountains and Kittanning, PA along the Kittanning Path. Taking a right through the gap to climb up the escarpment was a bit easier than either steep narrow creek beds straight ahead.. USGS overview indicating Kittanning Gap's, Pennsylvania location near Altoona, PA and showing the PRR Horseshoe Curve.png
Location of Kittanning Gap after GNIS finding of 'Kittanning Gap, Pennsylvania' seen in USGS National Map viewer screenshot. The gap is located effectively in a western suburb of Altoona, PA.
  The maps on this page also are showing the nearby PRR Horseshoe Curve which crosses three other gaps and the confluence of Kittanning Run with .
 The Kittanning Gap gives this 'choice way' of climbing the escarpment to wagons or mule trains on the way to the west side of the Allegheny Mountains and Kittanning, PA along the Kittanning Path. Taking a right through the gap to climb up the escarpment was a bit easier than either steep narrow creek beds straight ahead..
USGS combined topological and relief map mode view with search object 'Kittanning Run'. The Web software identifies the search item with short yellow point icon containing the 'A' (circled). Note that this 'official USGS confluence' is several miles from the official USGS Kittanning Gap.
* The dark trace forming a hairpin turn directly below that marker is the Pennsylvania Railroad's famous Horseshoe Curve. USGS National Map viewer showing Kittanning Run, Pennsylvania location near Altoona--MIxed Mode topo+Sat.png
USGS combined topological and relief map mode view with search object 'Kittanning Run'. The Web software identifies the search item with short yellow point icon containing the 'A' (circled). Note that this 'official USGS confluence' is several miles from the official USGS Kittanning Gap.
 The dark trace forming a hairpin turn directly below that marker is the Pennsylvania Railroad's famous Horseshoe Curve.