1.
National Natural Landmark
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The National Natural Landmarks Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best examples of biological and geological features in both public and private ownership, the program was established on May 18,1962, by United States Secretary of the Interior Stewart Udall. The program aims to encourage and support voluntary preservation of sites that illustrate the geological and ecological history of the United States and it also hopes to strengthen the publics appreciation of the countrys natural heritage. As of November 2016,599 sites have been added to the National Registry of National Landmarks, the registry includes nationally significant geological and ecological features in 48 states, American Samoa, Guam, Puerto Rico, and the Virgin Islands. The National Park Service administers the NNL Program and if requested, land acquisition by the federal government is not a goal of this program. National Natural Landmarks are nationally significant sites owned by a variety of land stewards, the legislative authority for the National Natural Landmarks Program stems from the Historic Sites Act of August 21,1935, the program is governed by federal regulations. The NNL Program does not have the features of Section 106 of the National Historic Preservation Act of 1966. Thus, designation of a National Natural Landmark presently constitutes only an agreement with the owner to preserve, insofar as possible, administration and preservation of National Natural Landmarks is solely the owners responsibility. Either party may terminate the agreement after they notify the other, the UKs Site of Special Scientific Interest list is a rough equivalent. The NNL designation is made by the Secretary of the Interior after in-depth scientific study of a potential site, all new designations must have owner concurrence. The selection process is rigorous, to be considered for NNL status, since establishment of the NNL program, a multi-step process has been used to designate a site for NNL status. Since 1970, the steps have constituted the process. A natural area inventory of a region is completed to identify the most promising sites. After landowners are notified that the site is being considered for NNL status, the evaluation report is peer reviewed by other experts to assure its soundness. The report is reviewed further by National Park Service staff, the site is reviewed by the Secretary of the Interiors National Park Advisory Board to determine that the site qualifies as an NNL. The findings are provided to the Secretary of the Interior who approves or declines, landowners are notified a third time informing them that the site has been designated an NNL. Each major natural history theme can be subdivided into various sub-themes. The NNL program does not require designated properties to be owned by public entities, lands under almost all forms of ownership or administration have been designated—federal, state, local, municipal and private
2.
Canyon
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A canyon or gorge is a deep cleft between escarpments or cliffs resulting from the erosive activity of a river over geologic timescales. A canyon may also refer to a rift between two peaks, such as those in ranges including the Rocky Mountains, the Alps. Usually a river or stream and erosion carve out such splits between mountains, examples of mountain-type canyons are Provo Canyon in Utah or Yosemite National Park in Californias Sierra Nevada. Canyons within mountains, or gorges that have an opening on one side are called box canyons. Slot canyons are very narrow canyons, often with smooth walls, steep-sided valleys in the seabed of the continental slope underwater are referred to as submarine canyons. Unlike canyons on land, submarine canyons are thought to be formed by turbidity currents, the word canyon is Spanish in origin, with the same meaning. The word canyon is used in North America while the words gorge and ravine are used in Europe and Oceania, though gorge. In the United States, place names generally use canyon in the southwest and gorge in the northeast, in Canada, a gorge is usually narrow while a ravine is more open and often wooded. The military-derived word defile is occasionally used in the United Kingdom, most canyons were formed by a process of long-time erosion from a plateau or table-land level. The cliffs form because harder rock strata that are resistant to erosion, Canyons are much more common in arid than in wet areas because physical weathering has a more localized effect in arid zones. The wind and water from the combine to erode and cut away less resistant materials such as shales. The freezing and expansion of water also serves to help form canyons, water seeps into cracks between the rocks and freezes, pushing the rocks apart and eventually causing large chunks to break off the canyon walls, in a process known as frost wedging. Canyon walls are formed of resistant sandstones or granite. Sometimes large rivers run through canyons as the result of geological uplift. These are called entrenched rivers, because they are unable to alter their course. In the United States, the Colorado River in the Southwest, Canyons often form in areas of limestone rock. As limestone is soluble to an extent, cave systems form in the rock. When these collapse, a canyon is left, as in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire, England
3.
Caprock Escarpment
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In Texas, the escarpment stretches around 200 mi south-southwest from the northeast corner of the Texas Panhandle near the Oklahoma border. The escarpment is especially notable, from north to south, in Briscoe, Floyd, Motley, Crosby, Dickens, Garza, and Borden counties. In New Mexico, there is a prominent escarpment along the northernmost extension of the Llano Estacado, especially to the south of San Jon and Tucumcari, both in Quay County, New Mexico. Along the western edge of the Llano Estacado, the portion of the escarpment that stretches from Caprock to Maljamar, the escarpment is made of Caliche — a layer of calcium carbonate that resists erosion. In some places, the escarpment rises around 1,000 ft above the plains to the east, the escarpments features formed by erosion from rivers and streams, creating arroyos and highly diverse terrain, including the large Palo Duro Canyon southeast of Amarillo, Texas. One will notice the change in elevation of several hundred feet while crossing the Caprock Escarpment on Interstate 40 between Adrian, Texas and San Jon, New Mexico, Caprock Canyons State Park and Trailway, located near Quitaque, opened in 1982. A65 mi trail was developed within the park in 1992, along the trail is Clarity Tunnel, home to a large colony of Mexican free-tailed bats. Caprock from the Handbook of Texas Online Photos of the Llano Estacado, West Texas, and Eastern New Mexico
4.
Texas Panhandle
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The Texas Panhandle is a region of the U. S. state of Texas consisting of the northernmost twenty-six counties in the state. The panhandle is an area bordered by New Mexico to the west and Oklahoma to the north. The Handbook of Texas defines the border of Swisher County as the southern boundary of the Texas Panhandle region. Its land area is 25,823.89 sq mi, the Texas Panhandle is slightly larger in size than the US State of West Virginia. There is an additional 62.75 sq mi of water area and its population as of the 2010 census was 427,927 residents, or 1.7 percent of the states total population. As of the 2010 census, the density for the region was 16.6 per square mile. The Panhandle is distinct from North Texas, which is farther southeast, West of the Caprock Escarpment and north and south of the Canadian River breaks, the surface of the Llano Estacado is rather flat. South of the city of Amarillo, the level terrain gives way to Palo Duro Canyon and this colorful canyon was carved by the Prairie Dog Town Fork Red River. North of Amarillo lies Lake Meredith, a reservoir created by Sanford Dam on the Canadian River, the lake, along with the Ogallala Aquifer, provides drinking water and irrigation for this moderately dry area of the high plains. Interstate Highway 40 passes through the panhandle, and also passes through Amarillo, the highway passes through Deaf Smith, Oldham, Potter, Carson, Gray, Donley, and Wheeler Counties. The Texas Panhandle has been identified in the early 21st century as one of the fastest-growing windpower-producing regions in the nation because of its strong, steady winds. Before the rise of Amarillo, the three towns of the Panhandle were Clarendon in Donley County, Mobeetie in Wheeler County. Clarendon moved itself after it was overlooked by the Fort Worth, Mobeetie was reduced even below its original small size with the closure of the United States Armys Fort Elliott in 1890. Tascosa was ruined by the location of the railroad too far north of the town, as of the census of 2000, approximately 402,862 people lived in the panhandle. Of these,68. 9% were non-Hispanic White,23. 8% were Hispanic, only 2. 7% were of some other ethnicity. 92. 3% of inhabitants claimed native birth, and 8. 9% were veterans of the United States armed forces,49. 9% of the population was male, and 50. 1% was female. 13. 2% of the population were 65 years of age or older and it was one of the first regions of the state to break away from its Democratic roots, though Democrats continued to do well at the local level well into the 1980s. However, Republicans now dominate every level of government, holding nearly every elected post above the county level, in the 2008 Presidential Election, John McCain received 78. 82% of the vote, as compared with Barack Obamas 20. 48% share of the vote
5.
Amarillo, Texas
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Amarillo is the 14th-most populous city in the state of Texas, in the United States. It is also the largest city in the Texas Panhandle, a portion of the city extends into Randall County. The population was 190,695 at the 2010 census, the Amarillo metropolitan area has an estimated population of 236,113 in four counties. Amarillo, originally named Oneida, is situated in the Llano Estacado region, the availability of the railroad and freight service provided by the Fort Worth and Denver City Railroad contributed to the citys growth as a cattle-marketing center in the late 19th century. The city was once the self-proclaimed Helium Capital of the World for having one of the countrys most productive helium fields, the city is also known as The Yellow Rose of Texas, and most recently Rotor City, USA for its V-22 Osprey hybrid aircraft assembly plant. Amarillo operates one of the largest meat-packing areas in the United States, Pantex, the only nuclear weapons assembly and disassembly facility in the country, is also a major employer. The location of this facility also gave rise to the nickname Bomb City, the attractions Cadillac Ranch and Big Texan Steak Ranch are located adjacent to Interstate 40. U. S. Highway 66 also passed through the city, large ranches exist in the Amarillo area, among others, the defunct XIT Ranch and the still functioning JA Ranch founded in 1877 by Charles Goodnight and John George Adair. Goodnight continued the partnership for a time after Adairs death with Adairs widow, Cornelia Wadsworth Ritchie Adair, who was then the sole owner from 1887 until her death in 1921. Berry established a site for a town after he chose a section along the way of the Fort Worth and Denver City Railroad. Berry and Colorado City, Texas, merchants wanted to make their new site the regions main trading center. On August 30,1887, Berrys town site won the county seat election and was established in Potter County, availability of the railroad and freight service after the county seat election made the town a fast-growing cattle-marketing center. Early residents originally pronounced the name more similar to the Spanish pronunciation /ˌɑːməˈriːjoʊ/ ah-mə-REE-yoh. On June 19,1888, Henry B, sanborn also offered to trade lots in the new location to businesses in the original citys site and help with the expense of moving to new buildings. His incentives gradually won over people, who moved their businesses to Polk Street in the new commercial district, heavy rains almost flooded Berrys part of the town in 1889, prompting more people to move to Sanborns location. This eventually led to another county seat election making Sanborns town the new county seat in 1893, by the late 1890s, Amarillo had emerged as one of the worlds busiest cattle-shipping points, and its population grew significantly. The city became an elevator, milling, and feed-manufacturing center after an increase in production of wheat. Discovery of natural gas in 1918 and oil three years later brought oil and gas companies to the Amarillo area, the United States government bought the Cliffside Gas Field with high helium content in 1927 and the Federal Bureau of Mines began operating the Amarillo Helium plant two years later
6.
Canyon, Texas
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Canyon is a city in, and the county seat of, Randall County, Texas, United States. The population was 13,303 at the 2010 census and it is part of the Amarillo, Texas Metropolitan Statistical Area. Canyon is the home of West Texas A&M University and Panhandle-Plains Historical Museum, east of Canyon is the JA Ranch, founded in 1877 by Charles Goodnight and John George Adair and still under the ownership of the Adair heirs. According to the United States Census Bureau, Canyon has an area of 4.9 square miles. The city itself lies in a valley that eventually becomes Palo Duro Canyon to the east, at the 2010 census, there were 13,303 people,5,185 households and 2,924 families residing in the city. The population density was 2687.47 per square mile, there were 5,611 housing units at an average density of 1,133.54 per square mile. The racial makeup of the city was 88. 5% White,2. 4% African American,0. 7% Native American,1. 8% Asian,0. 1% Pacific Islander,4. 7% from other races, and 2% from two or more races. Hispanic or Latino of any race were 15. 7% of the population,31. 8% of all households were made up of individuals and 8. 9% had someone living alone who was 65 years of age or older. The average household size was 2.32 and the family size was 2.99. 21. 4% of the population were under the age of 18,18. 6% from 20 to 24,22. 3% from 25 to 44,15. 3% from 45 to 64, the median age was 25 years. For every 100 females there were 93.6 males, for every 100 females age 18 and over, there were 90.5 males. The median household income was $32,361 and the family income was $46,250. Males had an income of $34,338 versus $25,255 for females. The per capita income for the city was $16,292, about 8. 1% of families and 14. 3% of the population were below the poverty line, including 10. 2% of those under age 18 and 10. 3% of those age 65 or over. Public education in Canyon is served by the Canyon Independent School District, garner, editor in chief of Blacks Law Dictionary, author, and teacher. Grandson to Meade F. Griffin of the Texas Supreme Court and Court of Criminal Appeals, georgia OKeeffe, artist, lived first in Amarillo and then Canyon, having been inspired by the natural beauty of the Palo Duro country. Roy Whittenburg, businessman, newspaper publisher, and U. S. Senate candidate in 1958, city of Canyon City-Data Handbook of Texas Online
7.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
8.
Mesa
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Mesa is the American English term for tableland, an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape and it may also be called a table hill, table-topped hill or table mountain. It is larger than a butte, which it resembles closely. Examples are also found in other nations including Spain, Sardinia, North and South Africa, Arabia, India. Grand Mesa is a mesa located in western Colorado in the Southwest United States. Cerro Negro is a mesa in Argentina, the term mesa is used throughout the United States to describe a flat-topped mountain or hill. Mesas form by weathering and erosion of layered rocks that have been uplifted by tectonic activity. This process is called differential erosion, the most resistant rock types include sandstone, conglomerate, quartzite, basalt, chert, limestone, lava flows and sills. Lava flows and sills, in particular, are resistant to weathering and erosion. The less resistant rock layers are made up of shale. The differences in strength of rock layers is what gives mesas their distinctive shape. Less resistant rocks are eroded away on the surface into valleys, a large area of very resistant rock, such as a sill may shield the layers below it from erosion while the softer rock surrounding it is eroded into valleys, thus forming a caprock. Differences in rock type also reflect on the sides of a mesa, as instead of smooth slopes, the more resistant layers form the cliffs, or stairsteps, while the less resistant layers form gentle slopes, or benches, between the cliffs. Cliffs retreat and are cut off from the main cliff, or plateau. When the cliff edge does not retreat uniformly, but instead is indented by headward eroding streams, as the underlying shale erodes away, it can no longer support the overlying cliff layers, which collapse and retreat. When the caprock has caved away to the point where only a little remains, a transitional zone on Mars, known as the fretted terrain, lies between highly cratered highlands and less cratered lowlands. The younger lowland exhibits steep walled mesas and knobs, the mesa and knobs are separated by flat lying lowlands. They are thought to form from ice-facilitated mass wasting processes from ground or atmospheric sources, the mesas and knobs decrease in size with increasing distance from the highland escarpment
9.
Grand Canyon
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The Grand Canyon is a steep-sided canyon carved by the Colorado River in the U. S. state of Arizona in North America. President Theodore Roosevelt was a proponent of preservation of the Grand Canyon area. The Grand Canyon is 277 miles long, up to 18 miles wide, since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs, simultaneously deepening and widening the canyon. For thousands of years, the area has been inhabited by Native Americans. The Pueblo people considered the Grand Canyon a holy site, the first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540. It is not the deepest canyon in the world, however, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the sequence of ancient rocks that are well preserved and exposed in the walls of the canyon. These rock layers record much of the geologic history of the North American continent. Uplift associated with mountain formation later moved these sediments thousands of feet upward, the higher elevation has also resulted in greater precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid. The uplift of the Colorado Plateau is uneven, and the Kaibab Plateau that Grand Canyon bisects is over a one thousand feet higher at the North Rim than at the South Rim. Almost all runoff from the North Rim flows toward the Grand Canyon, the result is deeper and longer tributary washes and canyons on the north side and shorter and steeper side canyons on the south side. Temperatures on the North Rim are generally lower than those on the South Rim because of the greater elevation, heavy rains are common on both rims during the summer months. Access to the North Rim via the route leading to the canyon is limited during the winter season due to road closures. The Grand Canyon is part of the Colorado River basin which has developed over the past 40 million years, a recent study places the origins of the canyon beginning about 17 million years ago. Previous estimates had placed the age of the canyon at 5–6 million years, the study, which was published in the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is an amount of controversy because this research suggests such a substantial departure from prior widely supported scientific consensus. In December 2012, a study published in the journal Science claimed new tests had suggested the Grand Canyon could be as old as 70 million years, the canyon is the result of erosion which exposes one of the most complete geologic columns on the planet. The major geologic exposures in the Grand Canyon range in age from the 2-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 230-million-year-old Kaibab Limestone on the Rim
10.
Geologic map
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A geologic map or geological map is a special-purpose map made to show geological features. Rock units or geologic strata are shown by color or symbols to indicate where they are exposed at the surface, stratigraphic contour lines may be used to illustrate the surface of a selected stratum illustrating the subsurface topographic trends of the strata. Isopach maps detail the variations in thickness of stratigraphic units and it is not always possible to properly show this when the strata are extremely fractured, mixed, in some discontinuities, or where they are otherwise disturbed. Rock units are represented by colors. Instead of colors, certain symbols can be used, different geologic mapping agencies and authorities have different standards for the colors and symbols to be used for rocks of differing types and ages. Geologists take two major types of measurements, orientations of planes and orientations of lines. Orientations of planes are often measured as a strike and dip, while orientations of lines are measured as a trend. The angle that the bed makes with the horizontal, along the dip direction, is next to the dip line. In the azimuthal system, strike and dip are often given as strike/dip, trend and plunge are used for linear features, and their symbol is a single arrow on the map. The arrow is oriented in the direction of the linear feature and at the end of the arrow. Trend and plunge are often notated as PLUNGE → TREND, the oldest preserved geologic map is the Turin papyrus, which shows the location of building stone and gold deposits in Egypt. The earliest geologic map of the era is the 1771 Map of Part of Auvergne, or figures of, The Current of Lava in which Prisms, Balls. To be used with Mr. Demarests theories of this hard basalt, pasumot and Daily, Geological Engineers of the King. This map is based on Nicolas Desmarests 1768 detailed study of the geology and eruptive history of the Auvergne volcanoes and he identified both landmarks as features of extinct volcanoes. The 1798 report was incorporated in the 1771 Royal Academy of Science compendium, the first geological map of the U. S. was produced in 1809 by William Maclure. In 1807, Maclure undertook the task of making a geological survey of the United States. He traversed and mapped nearly every state in the Union, during the rigorous two-year period of his survey, he crossed and recrossed the Allegheny Mountains some 50 times. Maclures map shows the distribution of five classes of rock in what are now only the states of the present-day US
11.
West Texas
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West Texas is a loosely defined part of the U. S. state of Texas, generally encompassing the arid and semiarid lands west of a line drawn between the cities of Fort Worth and Del Rio. There is no consensus on the boundary between eastern and western Texas, West Texas is often subdivided according to distinct physiographic features. The portion of West Texas that lies west of the Pecos River is often referred to as Far West Texas or the Trans-Pecos, the Trans-Pecos lies within the Chihuahuan Desert, the most arid portion of the state. Another part of West Texas is the Llano Estacado, a vast region of high, level plains extending into Eastern New Mexico, to the east of the Llano Estacado lies the “redbed country” of the Rolling Plains and to the south of the Llano Estacado lies the Edwards Plateau. The Rolling Plains and the Edwards Plateau subregions act as transitional zones between eastern and western Texas, the counties included in the West Texas region vary depending on the organization. West Texas has a lower population density than the rest of the state. It was once inhabited by nomadic Native American tribes, such as the Apache, Comanche, and Kiowa. This period was marked with savage war waged between the US Army, frontier Texans, and the Texas Rangers on one side and native peoples on the other. During the later 19th century, the population of Americans. This period was marked by the mapping and geographical intelligence collection of a denied area held by hostile Indian tribes. In turn, the Comanche way of war reached its zenith, having either subjugated or defeated the other Indian clans. In contrast, the support by the US government of Americans settlement. By the end of the 19th century, West Texas had been pacified of hostile Indians, leaving its turbulent history to what remained of outlaw Texans and people such as Judge Roy Bean. With the defeat of the Comanche and their allies and their removal upon demand by Texas from the state, the area was settled by Texans. These decades marked the last great cattle drives, the zenith of American cowboys, small farmers and ranchers battling sheepherders. This continuing socioeconomic trends resulted in the region having a mix of Mexican American and American communities of the modern day. As a result of historical development, many Mexican Americans still have close family ties in Mexico. Of American settlers, during the migration era, the vast majority were either East Texans or other Southerners going west for new opportunities
12.
Erosion
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In earth science, erosion is the action of surface processes that remove soil, rock, or dissolved material from one location on the Earths crust, then transport it away to another location. Eroded sediment or solutes may be transported just a few millimetres, the rates at which such processes act control how fast a surface is eroded. Feedbacks are also possible between rates of erosion and the amount of eroded material that is carried by, for example. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, while erosion is a natural process, human activities have increased by 10-40 times the rate at which erosion is occurring globally. At well-known agriculture sites such as the Appalachian Mountains, intensive farming practices have caused erosion up to 100x the speed of the rate of erosion in the region. Excessive erosion causes both on-site and off-site problems, on-site impacts include decreases in agricultural productivity and ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of bodies, as well as sediment-related damage to roads. Intensive agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion, however, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall, and the surface runoff which may result from rainfall, produces four types of soil erosion, splash erosion, sheet erosion, rill erosion. Splash erosion is generally seen as the first and least severe stage in the erosion process. In splash erosion, the impact of a falling raindrop creates a crater in the soil. The distance these soil particles travel can be as much as 0.6 m vertically and 1.5 m horizontally on level ground. If the soil is saturated, or if the rate is greater than the rate at which water can infiltrate into the soil. If the runoff has sufficient flow energy, it will transport loosened soil particles down the slope, sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes, generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are typically of the order of a few centimetres or less and this means that rills exhibit hydraulic physics very different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when water accumulates and rapidly flows in narrow channels during or immediately after heavy rains or melting snow
