A joint is a break of natural origin in the continuity of either a layer or body of rock that lacks any visible or measurable movement parallel to the surface of the fracture. Although they can occur singly, they most occur as joint sets and systems. A joint set is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of the orientations and physical properties. A joint system consists of two or more intersecting joint sets; the distinction between joints and faults hinges on the terms visible or measurable, a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the fracture; as a result, a joint may have been created by either strict movement of a rock layer or body perpendicular to the fracture or by varying degrees of lateral displacement parallel to the surface of the fracture that remains “invisible” at the scale of observation. Joints are among the most universal geologic structures as they are found in most every exposure of rock.
They vary in appearance and arrangement, occur in quite different tectonic environments. The specific origin of the stresses that created certain joints and associated joint sets can be quite ambiguous and sometimes controversial; the most prominent joints occur in the most well-consolidated and competent rocks, such as sandstone, limestone and granite. Joints may be open fractures or filled by various materials. Joints infilled by precipitated minerals are called veins and joints filled by solidified magma are called dikes. Joints result from brittle fracture of a rock body or layer as the result of tensile stresses; these tensile stresses either were induced or imposed from outside, e.g. by the stretching of layers. When tensional stresses stretch a body or layer of rock such that its tensile strength is exceeded, it breaks; when this happens the rock fractures in a plane parallel to the maximum principal stress and perpendicular to the minimum principal stress. This leads to the development of a single sub-parallel joint set.
Continued deformation may lead to development of one or more additional joint sets. The presence of the first set affects the stress orientation in the rock layer causing subsequent sets to form at a high angle 90°, to the first set. Joints are classified either by the processes responsible for their geometry; the geometry of joints refers to the orientation of joints as either plotted on stereonets and rose-diagrams or observed in rock exposures. In terms of geometry, three major types of joints, nonsystematic joints, systematic joints, columnar jointing are recognized. Nonsystematic joints are joints that are so irregular in form and orientation that they cannot be grouped into distinctive, through-going joint sets. Systematic joints are planar, joints that can be traced for some distance, occur at evenly spaced distances on the order centimeters, tens of meters, or hundreds of meters; as a result, they occur as families of joints. Exposures or outcrops within a given area or region of study contains two or more sets of systematic joints, each with its own distinctive properties such as orientation and spacing, that intersect to form well-defined joint systems.
Based upon the angle at which joint sets of systematic joints intersect to form a joint system, systematic joints can be subdivided into conjugate and orthogonal joint sets. The angles at which joint sets within a joint system intersect is called by structural geologists as the dihedral angles; when the dihedral angles are nearly 90° within a joint system, the joint sets are known as orthogonal joint sets. When the dihedral angles are from 30 to 60° within a joint system, the joint sets are known as conjugate joint sets. Within regions that have experienced tectonic deformation, systematic joints are associated with either layered or bedded strata, folded into anticlines and synclines; such joints can be classified according to their orientation in respect to the axial planes of the folds as they commonly form in a predictable pattern with respect to the hinge trends of folded strata. Based upon their orientation to the axial planes and axes of folds, the types of systematic joints are: Longitudinal joints – Joints which are parallel to fold axes and fan around the fold.
Cross-joints – Joints which are perpendicular to fold axes. Diagonal joints – Joints which occur as conjugate joint sets that trend oblique to the fold axes. Strike joints – Joints which trend parallel to the strike of the axial plane of a fold. Cross-strike joints – Joints which cut across the axial plane of a fold. Columnar jointing is a distinctive type of joints that join together at triple junctions either at or about 120° angles; these joints split a rock body into long, columns. Such columns are hexagonal, although 3-, 4-, 5- and 7-sided columns are common; the diameter of these prismatic columns range from a few centimeters to several metres. They are oriented perpendicular to either the upper surface and base of lava flows and the contact of the tabular igneous bodies with the surrounding rock; this type of jointing is typical of thick lava flows and shallow di
A rail trail is the conversion of a disused railway track into a multi-use path for walking and sometimes horse riding and snowmobiling. The characteristics of abandoned railways—flat, long running through historical areas—are appealing for various developments; the term sometimes covers trails running alongside working railways. Some shared trails are segregated, with the segregation achieved without separation. Many rail trails are long-distance trails. A rail trail may still include rails, such as light streetcar. By virtue of their characteristic shape, some shorter rail trails are known as greenways and linear parks; the only carrier to exist in Bermuda folded in 1948 and was converted to a rail trail in 1984. Some of the former right of way has been converted for automobile traffic, but 18 miles are reserved for pedestrian use and bicycles on paved portions; the rail bed spans the length of the island, connected Hamilton to St. George's and several villages, though several bridges are derelict, causing the trail to be fragmented.
The Kettle Valley Rail Trail in British Columbia uses a rail corridor, built for the now-abandoned Kettle Valley Railway. The trail was developed during the 1990s after the Canadian Pacific Railway abandoned train service; the longest rail trail in Canada is the Newfoundland T'Railway that covers a distance of 883 km ). Protected as a linear park under the provincial park system, the T'Railway consists of the railbed of the historic Newfoundland Railway as transferred from its most recent owner, Canadian National Railway, to the provincial government after rail service was abandoned on the island of Newfoundland in 1988; the rail corridor stretches from Channel-Port aux Basques in the west to St. John's in the east with branches to Stephenville, Bonavista and Carbonear. Following the abandonment of the Prince Edward Island Railway in 1989, the government of Prince Edward Island purchased the right-of-way to the entire railway system; the Confederation Trail was developed as a tip-to-tip walking/cycling gravel rail trail which doubles as a monitored and groomed snowmobile trail during the winter months, operated by the PEI Snowmobile Association.
In Quebec, Le P'tit Train du Nord runs 200 km from Saint-Jérôme to Mont-Laurier. In Toronto, there are the Beltline Trail and the West Toronto Railpath. In central Ontario, the former Victoria Railway line, which runs 89 kilometres from the town of Lindsay, north to the village of Haliburton, in Haliburton County, serves as a public recreation trail, it can be used for cross country skiing and snowmobiling in the winter months, walking and horse riding from spring to autumn. The majority of the rail trail passes through sparsely populated areas of the Canadian Shield, with historic trestle bridges crossing several rivers; the old Sarnia Bridge in St. Marys, was re-purposed as part of the Grand Trunk Trail; the former Grand Trunk Railway viaduct was purchased from Canadian National Railway in 1995. The Grand Trunk Trail was opened in 1998 with over 3 km of paved, accessible trail. In 2012, The re-purposing of the Sarnia Bridge was inducted into the North America Railway Hall of Fame. A railroad between Gateway Road and Raleigh Street in Winnipeg, was turned into a 7 km asphalt trail in 2007.
It is called the Northeast Pioneers Greenway, has plans for expansion into East St. Paul, to Birds Hill Park. A considerable part of the Trans Canada Trail are repurposed defunct rail lines donated to provincial governments by CP and CN rail rebuilt as walking trails; the main section runs along the southern areas of Canada connecting most of Canada's major cities and most populous areas. There is a long northern arm which runs through Alberta to Edmonton and up through northern British Columbia to Yukon; the trail is multi-use and depending on the section may allow hikers, horseback riders, cross country skiers and snowmobilers. In North America, the decades-long consolidation of the rail industry led to the closure of a number of uneconomical branch lines and redundant mainlines; some were maintained as short line railways. The first abandoned rail corridor in the United States converted into a recreational trail was the Elroy-Sparta State Trail in Wisconsin, which opened in 1967; the following year the Illinois Prairie Path opened.
The conversion of rails to trails hastened with the federal government passing legislation promoting the use of railbanking for abandoned railroad corridors in 1983, upheld by the U. S. Supreme Court in 1990; this process preserves rail corridors for possible future rail use with interim use as a trail. By the 1970s main lines were being sold or abandoned; this was true when regional rail lines merged and streamlined their operations. As both the supply of potential trails increased and awareness of the possibilities rose, state governments, conservation authorities, private organizations bought the rail corridors to create, expand or link green spaces; the longest developed rail trail is the 240 miles Katy Trail in Missouri. When complete, the Cowboy Trail in Nebraska will become the longest; the Beltline, in Atlanta, Georgia, is under construction. In 2030, its anticipated year of completion, it will be one of the longest continuous trails; the Atlanta BeltLine is a sustainable redevelopment project that will provide a network of public parks, multi-use trails and transit along a historic 22-mile railroad corridor circling downtown and connecting many neigh
Santa Fe, Prescott and Phoenix Railway
The Santa Fe, Prescott and Phoenix Railway was a common carrier railroad that became an operating subsidiary of the Atchison and Santa Fe Railway in Arizona. At Ash Fork, the SFP&P connected with Santa Fe's operating subsidiary, the Atlantic & Pacific Railroad mainline, that ran from California to Chicago; the SFP&P's 195-mile line extended the Santa Fe Railway south into Phoenix. The SFP&P extended another 100 miles to the east from Phoenix to Florence and Winkelman via the Phoenix and Eastern Railroad; the SFP&P served several mines in the Prescott area through its various subsidiary railroads. On December 28, 1911, the line was merged into Atchison and Santa Fe Railway's non-operating subsidiary of the California and Santa Fe Railway. Today the line from Ash Fork to Phoenix is operated by the BNSF Railway. Due to its many winding curves and bridges, the route is popularly known as the Peavine; the SFP&P was chartered on May 27, 1891. Construction commenced on August 1892, from the Atlantic & Pacific connection at Ash Fork.
By April 1893 trains were operating between Ash Prescott. On March 13, 1895, the line ran all the way to Phoenix. On June 30, 1899, the SFP&P began operating the Prescott and Eastern Railroad that ran between Entro to Mayer. In 1901–02 the SFP&P operated its subsidiary the Bradshaw Mountain Railroad. On November 27, 1904, the SFP&P started operating Santa Fe Railway's subsidiary, the Phoenix and Eastern Railroad between Phoenix - Florence - Winkelman; the SFP&P stopped operating the Phoenix & Eastern when Southern Pacific Railroad acquired the Phoenix–Winkelman line on March 13, 1907. On November 1, 1905, the SFP&P began operating the Arizona & California Railway that ran from a connection with the Santa Fe Railway in the Mojave Desert at Cadiz, California, to a connection with SFP&P at Matthie, Arizona. By the end of 1909 the Arizona & California was an operating subsidiary of the SFP&P, using 3 4-6-0 locomotives made by Brooks Locomotive Works. On December 29, 1911, the SFP&P was merged into the California and Santa Fe Railway, a non-operating subsidiary of the Santa Fe Railway.
The SFP&P operated a fleet of about 27 steam locomotives. 21 of the locomotives were Brooks Locomotive Works 4-6-0 steam locomotives built between 1893-1903. Most of these locomotives would be renumbered ATSF #2421-2435; the SFP&P had six Brooks Locomotive Works 2-8-0 steam locomotives built between 1904-1906. These locomotives would be renumbered ATSF #2439-2444. 1897–1911 by the Santa Fe, Prescott & Phoenix Railway 1912– by the Atchison, Topeka & Santa Fe Railway Ash Fork Prescott Kirkland Congress Wickenburg Phoenix Prescott & Eastern Railroad Entro - Dewey - Poland Junction - Mayer Bradshaw Mountain Railroad Poland Junction - Poland Mayer - Turkey Creek - Saddle - Crown King Phoenix and Eastern Railroad Phoenix - Mesa - Florence - Kelvin - Winkelman Arizona & California Railway Cadiz - Parker, Arizona - Bouse - Salome - MatthieThe Arizona & California gave ATSF a more direct route from Los Angeles to Phoenix. List of defunct Arizona railroads Myrick, David F.. Santa Fe to Phoenix. Wilmot, California: Signature Press.
ISBN 1-930013-05-1. Robertson, Donald B.. Encyclopedia of Western Railroad History: The Desert States: Arizona, New Mexico, Utah. Caldwell, Idaho: The Caxton Printers. P. 102. ISBN 0-87004-305-6. Walker, Mike. Steam Powered Video's Comprehensive Railroad Atlas of North America - Arizona & New Mexico. Kent, United Kingdom: Steam Powered Publishing. ISBN 1-874745-04-8. Schweiterman, Joseph P; when the Railroad Leaves Town: American Communities in the Age of Rail Line Abandonment, Volume 2. Truman State University Press. P. 8. ISBN 978-1-9311-1214-7
The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
Spheroidal weathering is a form of chemical weathering that affects jointed bedrock and results in the formation of concentric or spherical layers of decayed rock within weathered bedrock, known as saprolite. When saprolite is exposed by physical erosion, these concentric layers peel off as concentric shells much like the layers of a peeled onion. Within saprolite, spheroidal weathering creates rounded boulders, known as corestones or woolsack, of unweathered rock. Spheroidal weathering is called onion skin weathering, concentric weathering, spherical weathering, or woolsack weathering. Spheroidal weathering is the result of chemical weathering of systematically jointed, massive rocks, including granite, dolerite and sedimentary rocks such as silicified sandstone, it occurs as the result of the chemical alteration of such rocks along intersecting joints. The chemical alteration of the rock results in the formation of abundant secondary minerals such as kaolinite, serpentine and chlorite and a corresponding increase in the volume of the altered rock.
When the joints within bedrock form a 3-dimensional network, they subdivided it into separated blocks in the form of cubes or rectangles, that are bounded by these joints. Because water can penetrate the bedrock along these joints, the near-surface bedrock will be altered by weathering progressively inward along the faces of these blocks; the alteration by weathering of the bedrock will be greatest along the corners of each block, followed by the edges, the faces of the cube. The differences in weathering rates between the corners and faces of a bedrock block will result in the formation of spheroidal layers of altered rock that surround an unaltered rounded boulder-size core of unaltered rock known as a corestone or woolsack. Spheroidal weathering has been incorrectly attributed to various types of physical weathering. Erosion has removed the layers of altered rock and other saprolite surrounding corestones that were produced by spheroidal weathering; this leaves many corestones as freestanding boulders on the ground's surface.
The spheroidal weathering, which created these corestones and the enclosing saprolite occurred in the prehistoric past during periods of humid tropical climates. The removal of the saprolite by erosion and exposure of corestones as freestanding residual boulders, tors, or other landforms occurs many thousands of years and during vastly different climatic conditions. Depending on local environmental conditions, spheroidal weathering of bedrock blocks defined by tectonically induced joints and fractures may result in the formation of prominent and well-defined Liesegang rings within these blocks; these blocks consist of bedrock blocks, which are bounded on their periphery by joints and fractures, and, in sedimentary rocks, bedding planes above and below. Each Liesegang block consists of a unaltered core surrounded by concentric, alternating shells of iron-poor and iron-rich composition which make up the Liesegang rings; these iron-poor and iron-rich shells follow the configuration of the outer shape of the block and are sub-parallel to its sides.
The iron-rich and iron-poor shells vary in degree of cementation and, as a result, can produce box work weathering structures during subsequent erosion. The degree of development of Liesegang rings as the result of weathering depends upon the spacing of the joint systems, groundwater flow, local topography, bedrock composition, bed thickness. Exfoliation, a related form of weathering that creates domes. Exfoliating granite Weathering rind E. H. Jager, Wollsackverwitterung - interessante vulkanische Strukturen, Mögen Sie Pflanzen? Images of Spheroidal Weathering Swanson-Hysell, N. Featured Field Photo—Spheroidal weathering profile, Department of Earth and Planetary Science, University of California at Berkeley, Berkeley, CA 94720
National Recreation Trail
National Recreation Trail is a designation given to existing trails that contribute to health and recreation goals in the United States. Over 1,148 trails in all 50 U. S. states, available for public use and ranging from less than a mile to 485 miles in length, have been designated as NRTs on federal, state and owned lands. Trails may be nominated for designation as NRTs each year; the NRT online database includes information on most designated trails. National Recreational Trails are part of the National Trails System. Most NRTs are hiking trails. A few are water trails; the National Park Service and the United States Forest Service jointly administer the National Recreation Trails Program with help from a number of other federal and nonprofit partners, notably American Trails, the lead nonprofit for developing and promoting NRTs. The National Trails System Act of 1968 authorized creation of a national trail system composed of National Recreation Trails and National Scenic Trails. National Historic Trails were added in 1978.
While National Scenic Trails and National Historic Trails may only be designated by an act of Congress, National Recreation Trails may be designated by the Secretary of Interior or the Secretary of Agriculture to recognize exemplary trails of local and regional significance in response to an application from the trail's managing agency or organization. Through designation, these trails are recognized as part of America's national system of trails; the National Recreation Trail Program, an independent advocacy organization, supports designated NRTs with an array of benefits, including promotion, technical assistance, a newsletter, email alerts, networking. Its goal is to promote the use and care of existing trails and stimulate the development of new trails to create a national network of trails and realize the vision of "Trails for All Americans." A state-by-state index provide details on featured trails. The first-ever NRT Photo Contest was sponsored in 2003 by American Trails and is continuing each year.
A Request for Proposals for art projects on National Recreation Trails was undertaken. The National Trails System Act of 1968 National Recreation Trails Program Online Database of designated National Recreation Trails American Trails
Watson Lake (Arizona)
Watson Lake is one of two reservoirs at the Granite Dells, in Prescott, formed in the early 1900s when the Chino Valley Irrigation District built a dam on Granite Creek. The City of Prescott bought the reservoir and surrounding land in 1997 to preserve it as recreational land. Local rockclimbers use the granite cliffs above and adjacent to the lake for top-roping and lead climbing; the lake is the home of TriCity Prep Rowing Crew, a local high school team and only rowing team in Northern Arizona. Largemouth Bass Crappie Sunfish Catfish Carp List of lakes in Arizona U. S. Geological Survey Geographic Names Information System: Watson Lake Arizona Boating Locations Facilities Map Arizona Fishing Locations Map Video of Watson Lake "Arizona Fishin' Holes", Information and Education Division, Phoenix, AZ: Arizona Game and Fish Department, 2007