Ozark–St. Francis National Forest
The Ozark – St. Francis National Forest is a United States National Forest, located in the state of Arkansas, it is composed of Ozark National Forest in the Ozark Mountains. Each forest has distinct biological and geological differences. Together, the two forests are home to 23 developed campgrounds, include nine swimming areas, 395 miles of hiking trails, 370 miles of streams for fishing; the majority of the trails in what are now the Ozark National Forest and St. Francis National Forest were constructed under the Works Progress Administration and Civilian Conservation Corps; the Forest contains 11,000 acres of old-growth forests. The old-growth forests occur in the southern portion of the Forest on ridges and steep south-facing slopes and are dominated by Shortleaf Pine and various oaks, including Post Oak, Blackjack Oak, Eastern Black Oak, White Oak, Northern Red Oak; the Forest is home to six different endangered species. Several National Scenic Byways cross the Ozark–St. Francis National Forest, including the Scenic 7 Byway which runs from Missouri to Louisiana, 60 miles of which are within the Ozark National Forest.
Scenic 7 Byway offers the greatest variety of Ozark topography and scenic vistas. The Ozark Highlands Byway provides access to the Mulberry River, Big Piney Creek, Buffalo National River for fisherman and canoeists; the Mount Magazine Byway offers scenic overlooks of the Arkansas River Valley, the Sylamore Scenic Byway offers a scenic drive to the Blanchard Springs Caverns. Forest headquarters are located in Arkansas; the Ozark National Forest encompasses 1,200,000 acres in the scenic Ozark Mountains in northern Arkansas. The forest contains the tallest mountain in Arkansas, Mount Magazine, Blanchard Springs Caverns; the southern section of the forest lies along the Arkansas River Valley south to the Ouachita Mountains. The forest was created in 1908 by proclamation of President Theodore Roosevelt; the forest is home to over 500 species of trees and woody plants. Hardwoods, predominantly oak and hickory, comprise the majority of the forest; the forest contains several Wildlife Management Areas. The Ozark Highlands Trail and maintained by over 3,000 volunteers, is the longest hiking trail in the forest and extends for 165 miles from the Buffalo National River to Lake Fort Smith State Park in the far western portion of the state.
The forest contains several multi-use trails including the Pedestal Rock Trail and the Alum Cove Natural Bridge Trail and a few wheelchair-accessible trails. In addition to the hiking trails, the forest provides trails designated for horseback riding, mountain biking, all-terrain vehicles; the longest horse trail is the Sylamore Trail with a length of 80 miles. This trail passes over rocky bluffs, into deep hollows, across mountain streams; the Huckleberry Mountain Horse Trail has a stop at the Sorghum Hollow Horse Camp, built and maintained by local horsemen. Ozark National Forest is located in parts of 16 counties. In descending order of forestland they are Newton, Johnson, Crawford, Baxter, Madison, Van Buren, Washington, Benton and Marion counties. There are local ranger district offices located in Clarksville, Jasper, Mountain View and Paris. There are five designated wilderness areas lying within Ozark National Forest that are part of the National Wilderness Preservation System. East Fork Wilderness Hurricane Creek Wilderness Leatherwood Wilderness Richland Creek Wilderness Upper Buffalo Wilderness The St. Francis National Forest was established on November 8, 1960 by President Dwight D. Eisenhower.
It covers 22,600 acres in eastern Arkansas along the Mississippi River, in Lee and Phillips counties, is one of the smallest national forests in the United States. There are local ranger district offices located in Marianna; the majority of the Forest is situated on Crowley's Ridge, but it extends into the low, flat lands along the Mississippi and St. Francis Rivers. St. Francis National Forest is the only place in the National Forest System where the public can enjoy the Mississippi River from the shoreline. While lacking the broad range of recreational activity available in other national forests, St. Francis National Forest is known for its fishing; the two largest lakes, Bear Creek Reservoir and Storm Creek Lake, enjoy large populations of Largemouth bass, Crappie and Channel catfish. Ouachita National Forest Ozark Mountain forests Sam's Throne Tom's Mill Fire An Illustrated History of the Ozark-St. Francis National Forests, 1908-1978 Wildernet: Ozark-St. Francis National Forest The National Forest Foundation's Conservation Plan for the Ozark National Forest
In structural geology, a syncline is a fold with younger layers closer to the center of the structure. A synclinorium is a large syncline with superimposed smaller folds. Synclines are a downward fold, termed a synformal syncline, but synclines that point upwards can be found when strata have been overturned and folded. On a geologic map, synclines are recognized as a sequence of rock layers, with the youngest at the fold's center or hinge and with a reverse sequence of the same rock layers on the opposite side of the hinge. If the fold pattern is circular or elongate, the structure is a basin. Folds form during crustal deformation as the result of compression that accompanies orogenic mountain building. Powder River Basin, Wyoming, US Sideling Hill roadcut along Interstate 68 in western Maryland, US, where the Rockwell Formation and overlying Purslane Sandstone are exposed Saou, a commune in the Drôme department in southeastern France The Southland Syncline in the southeastern corner of the South Island of New Zealand, including The Catlins and the Hokonui Hills Strathmore, Angus Syncline, Scotland Anticline Homocline Monocline Ridge-and-Valley Appalachians
Shale is a fine-grained, clastic sedimentary rock composed of mud, a mix of flakes of clay minerals and tiny fragments of other minerals quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility, it is the most common sedimentary rock. Shale exhibits varying degrees of fissility, breaking into thin layers splintery and parallel to the otherwise indistinguishable bedding plane because of the parallel orientation of clay mineral flakes. Non-fissile rocks of similar composition but made of particles smaller than 0.06 mm are described as mudstones or claystones. Rocks with similar particle sizes but with less clay and therefore grittier are siltstones. Shales are composed of clay minerals and quartz grain, are grey. Addition of variable amounts of minor constituents alters the color of the rock. Black shale results from the presence of greater than one percent carbonaceous material and indicates a reducing environment.
Black shale can be referred to as black metal. Red and green colors are indicative of ferric oxide, iron hydroxide, or micaceous minerals. Clays are the major constituent of other mudrocks; the clay minerals represented are kaolinite and illite. Clay minerals of Late Tertiary mudstones are expandable smectites whereas in older rocks in mid- to early Paleozoic shales illites predominate; the transformation of smectite to illite produces silica, calcium, magnesium and water. These released elements form authigenic quartz, calcite, ankerite and albite, all trace to minor minerals found in shales and other mudrocks. Shales and mudrocks contain 95 percent of the organic matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale. Black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron and sulfur. Pyrite and amorphous iron sulfide along with carbon produce the black coloration; the process in the rock cycle which forms shale is called compaction.
The fine particles that compose shale can remain suspended in water long after the larger particles of sand have deposited. Shales are deposited in slow moving water and are found in lakes and lagoonal deposits, in river deltas, on floodplains and offshore from beach sands, they can be deposited in sedimentary basins and on the continental shelf, in deep, quiet water.'Black shales' are dark, as a result of being rich in unoxidized carbon. Common in some Paleozoic and Mesozoic strata, black shales were deposited in anoxic, reducing environments, such as in stagnant water columns; some black shales contain abundant heavy metals such as molybdenum, uranium and zinc. The enriched values are of controversial origin, having been alternatively attributed to input from hydrothermal fluids during or after sedimentation or to slow accumulation from sea water over long periods of sedimentation. Fossils, animal tracks/burrows and raindrop impact craters are sometimes preserved on shale bedding surfaces.
Shales may contain concretions consisting of pyrite, apatite, or various carbonate minerals. Shales that are subject to heat and pressure of metamorphism alter into a hard, metamorphic rock known as slate. With continued increase in metamorphic grade the sequence is phyllite schist and gneiss. Before the mid-19th century, the terms slate and schist were not distinguished. In the context of underground coal mining, shale was referred to as slate well into the 20th century. Bakken Formation Barnett Shale Bearpaw Formation Burgess Shale Marcellus Formation Mazon Creek fossil beds Oil shale – Organic-rich fine-grained sedimentary rock containing kerogen Shale gas Shale gas in the United States Wheeler Shale Wianamatta Shale Media related to Shale at Wikimedia Commons
The Rocky Mountains known as the Rockies, are a major mountain range in western North America. The Rocky Mountains stretch more than 4,800 kilometers from the northernmost part of British Columbia, in western Canada, to New Mexico in the Southwestern United States. Located within the North American Cordillera, the Rockies are somewhat distinct from the Pacific Coast Ranges, Cascade Range, the Sierra Nevada, which all lie farther to the west; the Rocky Mountains formed 80 million to 55 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate. The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age, humans began inhabiting the mountain range. After Europeans, such as Sir Alexander Mackenzie, Americans, such as the Lewis and Clark expedition, began exploring the range and furs drove the initial economic exploitation of the mountains, although the range itself never experienced dense population.
Public parks and forest lands protect much of the mountain range, they are popular tourist destinations for hiking, mountaineering, hunting, mountain biking and snowboarding. The name of the mountains is a translation of an Amerindian name, related to Algonquian; the first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, where they were called "Montagnes de Roche". The Rocky Mountains are defined as stretching from the Liard River in British Columbia south to the Rio Grande in New Mexico; the Rockies vary in width from 110 to 480 kilometres. The Rocky Mountains are notable for containing the highest peaks in central North America; the range's highest peak is Mount Elbert located in Colorado at 4,401 metres above sea level. Mount Robson in British Columbia, at 3,954 metres, is the highest peak in the Canadian Rockies; the eastern edge of the Rockies rises above the Interior Plains of central North America, including the Sangre de Cristo Mountains of New Mexico and Colorado, the Front Range of Colorado, the Wind River Range and Big Horn Mountains of Wyoming, the Absaroka-Beartooth ranges and Rocky Mountain Front of Montana and the Clark Range of Alberta.
The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City and the Bitterroots along the Idaho-Montana border. The Great Basin and Columbia River Plateau separate these subranges from distinct ranges further to the west. In Canada, the western edge of the Rockies is formed by the huge Rocky Mountain Trench, which runs the length of British Columbia from its beginnings in the middle Flathead River valley in western Montana to the south bank of the Liard River. Geographers define three main groups of the Canadian Rockies: the Continental Ranges, Hart Ranges, Muskwa Ranges; the Rockies do not extend into central British Columbia. Other mountain ranges continue beyond the Liard River, including the Selwyn Mountains in Yukon, the Brooks Range in Alaska, but those are not part of the Rockies, though they are part of the American Cordillera; the Continental Divide of the Americas is located in the Rocky Mountains and designates the line at which waters flow either to the Atlantic or Pacific Oceans.
Triple Divide Peak in Glacier National Park is so named because water falling on the mountain reaches not only the Atlantic and Pacific but Hudson Bay as well. Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River, which has its outlet on the Beaufort Sea of the Arctic Ocean. Human population is not dense in the Rocky Mountains, with an average of four people per square kilometer and few cities with over 50,000 people. However, the human population grew in the Rocky Mountain states between 1950 and 1990; the forty-year statewide increases in population range from 35% in Montana to about 150% in Utah and Colorado. The populations of several mountain towns and communities have doubled in the last forty years. Jackson, increased 260%, from 1,244 to 4,472 residents, in forty years; the rocks in the Rocky Mountains were formed. The oldest rock is Precambrian metamorphic rock. There is Precambrian sedimentary argillite, dating back to 1.7 billion years ago. During the Paleozoic, western North America lay underneath a shallow sea, which deposited many kilometers of limestone and dolomite.
In the southern Rocky Mountains, near present-day Colorado, these ancestral rocks were disturbed by mountain building 300 Ma, during the Pennsylvanian. This mountain-building produced the Ancestral Rocky Mountains, they consisted of Precambrian metamorphic rock forced upward through layers of the limestone laid down in the shallow sea. The mountains eroded throughout the late Paleozoic and early Mesozoic, leaving extensive deposits of sedimentary rock. Terranes began colliding with the western edge of North America in the Mississippian, causing the Antler orogeny. For 270 million years, the focus of the effects of plate collisions were near the edge of the North American plate boundary, far to the west of the Rocky Mountain region, it was. The current Rocky Mountains arose in the Laramide orogeny from between 55 Ma. For the Canadi
Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that
A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere to bend, by a process known as lithospheric flexure; the width and depth of the foreland basin is determined by the flexural rigidity of the underlying lithosphere, the characteristics of the mountain belt. The foreland basin receives sediment, eroded off the adjacent mountain belt, filling with thick sedimentary successions that thin away from the mountain belt. Foreland basins represent an endmember basin type, the other being rift basins. Space for sediments is provided by loading and downflexure to form foreland basins, in contrast to rift basins, where accommodation space is generated by lithospheric extension. Foreland basins can be divided into two categories: Peripheral foreland basins, which occur on the plate, subducted or underthrust during plate collision Examples include the North Alpine Foreland Basin of Europe, or the Ganges Basin of Asia Retroarc foreland basins, which occur on the plate that overrides during plate convergence or collision Examples include the Andean basins, or Late Mesozoic to Cenozoic Rocky Mountain Basins of North America DeCelles & Giles provide a thorough definition of the foreland basin system.
Foreland basin systems comprise three characteristic properties: An elongate region of potential sediment accommodation that forms on continental crust between a contractional orogenic belt and the adjacent craton in response to geodynamic processes related to subduction and the resulting peripheral or retroarc fold-thrust belt. The wedge-top sits on top of the moving thrust sheets and contains all the sediments charging from the active tectonic thrust wedge; this is. The foredeep is thickens toward the orogen. Sediments are deposited via distal fluvial, lacustrine and marine depositional systems; the forebulge and backbulge are not always present. When present, they are defined by regional unconformities as well as aeolian and shallow-marine deposits. Sedimentation is most rapid near the moving thrust sheet. Sediment transport within the foredeep is parallel to the strike of the thrust fault and basin axis; the motion of the adjacent plates of the foreland basin can be determined by studying the active deformation zone with which it is connected.
Today GPS measurements provide the rate. It is important to consider that present day kinematics are unlikely to be the same as when deformation began. Thus, it is crucial to consider non-GPS models to determine the long-term evolution of continental collisions and in how it helped develop the adjacent foreland basins. Comparing both modern GPS and non-GPS models allows deformation rates to be calculated. Comparing these numbers to the geologic regime helps constrain the number of probable models as well as which model is more geologically accurate within a specific region. Seismicity determines where active zones of seismic activity occur as well as measure the total fault displacements and the timing of the onset of deformation. Foreland basins form because as the mountain belt grows, it exerts a significant mass on the Earth’s crust, which causes it to bend, or flex, downwards; this occurs so that the weight of the mountain belt can be compensated by isostasy at the upflex of the forebulge.
The plate tectonic evolution of a peripheral foreland basin involves three general stages. First, the passive margin stage with orogenic loading of stretched continental margin during the early stages of convergence. Second, the "early convergence stage defined by deep water conditions", lastly a "later convergent stage during which a subaerial wedge is flanked with terrestrial or shallow marine foreland basins"; the temperature underneath the orogen weakens the lithosphere. Thus, the thrust belt is mobile and the foreland basin system becomes deformed over time. Syntectonic unconformities demonstrate tectonic activity. Foreland basins are filled with sediments. In the early stages, the foreland basin is said to be underfilled. During this stage, deep water and marine sediments, known as flysch, are deposited; the basin becomes filled. At this point, the basin enters the overfilled stage and deposition of terrestrial clastic sediments occurs; these are known as molasse. Sediment fill within the foredeep acts as an additional load on the continental lithosphere.
Although the degree to which the lithosphere relaxes over time is still controversial, most workers accept an elastic or visco-elastic rheology to describe the lithospheric deformation of the foreland basin. Allen & Allen describe a moving load system, one in which the deflectio
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation include drizzle, sleet, snow and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates", thus and mist are not precipitation but suspensions, because the water vapor does not condense sufficiently to precipitate. Two processes acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called "showers."Moisture, lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is active when freezing rain occurs. A stationary front is present near the area of freezing rain and serves as the foci for forcing and rising air.
Provided necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely stratus and cumulonimbus. The cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation is caused by convection; the movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
Precipitation is a major component of the water cycle, is responsible for depositing the fresh water on the planet. 505,000 cubic kilometres of water falls as precipitation each year. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres, but over land it is only 715 millimetres. Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Precipitation may occur on other celestial bodies, e.g. when it gets cold, Mars has precipitation which most takes the form of frost, rather than rain or snow. Precipitation is a major component of the water cycle, is responsible for depositing most of the fresh water on the planet. 505,000 km3 of water falls as precipitation each year, 398,000 km3 of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres. Mechanisms of producing precipitation include convective and orographic rainfall.
Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with the surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles, ice pellets and graupel; the dew point is the temperature to which a parcel must be cooled in order to become saturated, condenses to water. Water vapor begins to condense on condensation nuclei such as dust and salt in order to form clouds. An elevated portion of a frontal zone forces broad areas of lift, which form clouds decks such as altostratus or cirrostratus.
Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can form due to the lifting of advection fog during breezy conditions. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, evaporative cooling. Adiabatic cooling occurs when air expands; the air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain. Conductive cooling occurs when the air comes into contact with a colder surface by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath. Evaporative cooling occurs when moisture is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature, or until it reaches saturation; the main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet lan