Erosion
In earth science, erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, transports it to another location. This natural process is caused by the dynamic activity of erosive agents, that is, ice, air, plants and humans. In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind erosion, zoogenic erosion, anthropogenic erosion; the particulate breakdown of rock or soil into clastic sediment is referred to as physical or mechanical erosion. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Natural rates of erosion are controlled by the action of geological weathering geomorphic drivers, such as rainfall; the rates at which such processes act control. Physical erosion proceeds fastest on steeply sloping surfaces, rates may be sensitive to some climatically-controlled properties including amounts of water supplied, wind speed, wave fetch, or atmospheric temperature.
Feedbacks are possible between rates of erosion and the amount of eroded material, carried by, for example, a river or glacier. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, which control the arrival and emplacement of material at a new location. 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 natural 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 eventual end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses.
Water and wind erosion are the two primary causes of land degradation. Intensive agriculture, 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, the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, gully erosion. Splash erosion is seen as the first and least severe stage in the soil erosion process, followed by sheet erosion rill erosion and gully erosion. In splash erosion, the impact of a falling raindrop creates a small crater in the soil, ejecting soil particles; 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 rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs.
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. Where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are of the order of a few centimetres or less and along-channel slopes may be quite steep; this means that rills exhibit hydraulic physics different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when runoff water accumulates and flows in narrow channels during or after heavy rains or melting snow, removing soil to a considerable depth. Valley or stream erosion occurs with continued water flow along a linear feature; the erosion is both downward, deepening the valley, headward, extending the valley into the hillside, creating head cuts and steep banks.
In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain; the stream gradient becomes nearly flat, lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone
Wet Tropics of Queensland
The Wet Tropics of Queensland World Heritage Site consists of 8,940 km² of Australian wet tropical forests growing along the north-east Queensland portion of the Great Dividing Range. The Wet Tropics of Queensland meets all four of the criteria for natural heritage for selection as a World Heritage Site. World Heritage status was declared in 1988, on 21 May 2007 the Wet Tropics were added to the Australian National Heritage List; the tropical forests have the highest concentration of primitive flowering plant families in the world. Only Madagascar and New Caledonia, due to their historical isolation, have humid, tropical regions with a comparable level of endemism; the Wet Tropics rainforests are recognised internationally for their ancient ancestry and many unique plants and animals. Many plant and animal species in the Wet Tropics are found nowhere else in the world; the Wet Tropics has the oldest continuously surviving tropical rainforests on earth On 9 November 2012, the Australian Government acknowledged the Indigenous heritage of the area as being nationally significant.
The Aboriginal Rainforest People of the Wet Tropics of Queensland have lived continuously in the rainforest environment for at least 5000 years, this is the only place in Australia where Aboriginal people have permanently inhabited a tropical rainforest environment. The Wet Tropics of Queensland stretches in part from Townsville to Cooktown, running in close parallel to the Great Barrier Reef; the terrain is rugged. The Great Dividing Range and a number of small coastal ranges, tablelands, foothills and an escarpment dominate the landscape; the heritage site contains the northern section of the Queensland tropical rain forests including the Daintree Rainforest. 16 different structural types of rainforest have been identified. The World Heritage area includes Wallaman Falls. In total it spans 13 major river systems including the Annan, Daintree, Mulgrave, Johnstone, Herbert, Mitchell and Palmer River. Copperlode Falls Dam, Koombooloomba Dam and Paluma Dam are found within the World Heritage Area.
15% of the area is protected as national park. Among the national parks included within the Wet Tropics are: Barron Gorge National Park Black Mountain National Park Cedar Bay National Park Daintree National Park Edmund Kennedy National Park Girringun National Park Kirrama National Park Kuranda National Park Macalister Range National Park Wooroonooran National Parkand over 700 protected areas including owned land; the Wet Tropics Management Authority was established in 1983. The agency employed 20 staff in 2012 as a unit within the Department of Environment and Heritage Protection, it is headed by a board of directors responsible to the Wet Tropics Ministerial Council which contains both Queensland and Federal Government representatives. The site contains many unique features such as over 390 rare plant species, which includes 74 species that are threatened. There are at least 85 species that are endemic to the area, 13 different types of rainforest and 29 species of mangrove, more than anywhere else in the country.
Of the 19 families of primitive flowering plants worldwide, 12 are found in the Wet Tropics including two families found nowhere else. This includes at least 50 individual species which are endemic to the area.90 species of orchids have been noted. The large rare trees Stockwellia or Vic Stockwell's Puzzle Stockwellia quadrifida grow only in restricted areas of "well developed upland rain forest" in the Wet Tropics, they continue living today as descendants of, similar to, the ancient Gondwanan fossil species considered one of the Eucalypts' fossil ancestors, which diversified into so many different species forms of all the Eucalypt plants today. 65% of Australia's fern species are protected here, including all seven of the ancient fern species. 370 species of bird have been recorded in the area. 11 species of those are found nowhere else. The endangered southern cassowary and rare spotted-tailed quoll are some of the many threatened species, while the musky rat-kangaroo is one of 50 animal species that are unique to this area.
The musky rat-kangaroo is significant because it represents an early stage in the evolution of kangaroos. Other rare animals include brush-tailed bettong. 107 mammal species have been identified. Australia's rarest mammal, the tube nosed insectivorous murina florious bat, is found here. One quarter of Australia's rodent species are found within the Wet Tropics.113 species of reptiles including 24 endemic species are found in the area and there are 51 amphibian species, of which 22 are endemic. One reason for the high level of endemism is that the geomorphology is diverse, resulting in habitat islands where distinct subspecies have evolved; some species are endemic to groups of mountains. Rainfall in the area varies with elevation and orientation of the coastline being the major influences. Rainfall averages from 1,200 millimeters to over 8,000 mm annually; the highest mountains along the escarpment between Cairns and Tully receive the highest rainfall owing to orographic factors. Mount Bellenden Ker is the wettest recording station in the area with other high peaks and eastern slopes favouring high rainfall.
Most of the rainfall occurs from November to April. Tropical cyclones may impact the area; the expansion of the sugarcane industry in lowland plains poses a significant threat to some endangered ecosystems. Some are fragmented and their natural vegetation is degraded. Invasive pes
Ebor Falls
Ebor Falls is a tiered waterfall on the Guy Fawkes River, located near Ebor and about 37 kilometres north-east of Wollomombi on Waterfall Way in the New England region of New South Wales, Australia. The first lookout is on a sealed road 200 metres off the Waterfall Way; this viewing platform shows the upper falls tumbling 115 metres over 4 layers of columned basalt rock in two falls. The lower Ebor falls, 600 metres further on, plunge over Permian sedimentary rocks into a steep forested gorge below; the falls are a well known tourist attraction within Guy Fawkes River National Park, with viewing platforms of the falls and walking tracks, a rest area with barbecues, an information display, picnic tables and toilet. In 2008 the waterfalls were attracting up to 80,000 visitors each year. Camping is not permitted at Ebor Falls, however camping is available at nearby Cathedral Rock National Park; the falls were first protected in a recreation reserve in 1895. In September 2008 new lookout platforms were opened.
These replaced platforms that were destroyed by fire in 2007. List of waterfalls of Australia
Boundary Falls
The Boundary Falls is a waterfall, located within the Gibraltar Range National Park, adjacent to the Gwydir Highway in the New England region of New South Wales, Australia. The falls are located 63 kilometres east of Glen Innes and 95 kilometres west of Grafton, a campsite is located nearby on the site of a former sawmill within a dry open eucalypt forest. List of waterfalls of New South Wales
Geoscience Australia
Geoscience Australia is an agency of the Australian Government. It carries out geoscientific research; the agency is the government's technical adviser on all aspects of geoscience, custodian of the geographic and geological data and knowledge of the nation. On a user pays basis it produces geospatial products such as satellite imagery, it is a major contributor to the Australian Government's free, open data collections such as data.gov.au. The agency has six strategic priority areas: building Australia's resource wealth in order to maximise benefits from Australia's minerals and energy resources and into the future. Geoscience Australia came into being in 2001 when the Australian Surveying and Land Information Group merged with the Australian Geological Survey Organisation, its history dates back to Federation in 1901 when it was decided to set aside land for the national capital. This decision led to the establishment of the Australian Survey Office in 1910, when surveying began for the Australian Capital Territory.
AUSLIG's main function was to provide national geographic information. It was formed in 1987, when the Australian Survey Office joined with the Division of National Mapping, formed in 1947. Another important component of AUSLIG was the provision of satellite imagery to industry and government, started by the Australian Landsat Station in 1979, renamed the Australian Centre for Remote Sensing in 1986. AGSO's predecessor organisation the Bureau of Mineral Resources and Geophysics was established in 1946; the BMR was a geological survey with the main objective was the systematic geological and geophysical mapping of the continent as the basis for informed mineral exploration. Geoscience Australia's activities have expanded and today it has responsibility for meeting the Australian Government's geoscience requirements; this role takes the Agency well beyond its historic focus on resource development and topographic mapping to topics as diverse as natural hazards such as tsunami and earthquakes, environmental issues, including the impacts of climate change, groundwater research and coastal research, carbon capture and storage and vegetation monitoring as well as Earth observations from space.
Geoscience Australia's remit extends beyond the Australian landmass to Australia's vast marine jurisdiction. It has a free place name search and its earthquake monitoring services can be accessed; the Library is the premier geoscience library in Australia providing services to geoscience organisations, research centres, the mining and petroleum industries and the public. Geological Survey of South Australia Geological Survey of Western Australia List of national mapping agencies Geoscience Australia home page. Geoscience Australia in Google Cultural Institute As the cocky flies distance calculator International Map of the World XNATMAP's home page preserving NATMAP's history and maintaining contact with the people who were part of that history
Continental margin
The continental margin is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin is the shallow water area found in proximity to continent; the continental margin consists of three different features: the continental rise, the continental slope, the continental shelf. Continental margins constitute about 28% of the oceanic area; the continental shelf is the portion of the continental margin that transitions from the shore out towards to ocean. They are believed to make up 7 percent of the sea floor; the width of continental shelves worldwide varies from a 30 meters to 1500 kilometers. It is flat, ends at the shelf break, where there is a drastic increase in slope angle; the mean slope of continental shelves worldwide is 0° 07’ degrees, steeper closer to the coastline than it is near the shelf break. At the shelf break begins the continental slope, which can be one to five kilometers above the deep-ocean floor; the continental slope exhibits features called submarine canyons.
Submarine canyons cut into the continental shelves with near vertical slopes, continue to cut the morphology to the abyssal plain. The valleys are V-shaped, can sometime enlarge onto the continental shelf. At the base of the continental slope, there is a sudden decrease in slope, the sea floor begins to level out towards the abyssal plain; this portion of the seafloor is called the continental rise, marks the end of the continental margin. There are two types of continental margins: passive margins. Active margins are associated with lithospheric plate boundaries; these active margins can be convergent or transform margins, are places of high tectonic activity, including volcanoes and earthquakes. The West Coast of North America and South America are active margins. Active continental margins are narrow from coast to shelf break, with steep descents into trenches. Convergent active margins occur; the denser oceanic plate subducts below the less dense continental plate. Convergent active margins are the most common type of active margin.
Transform active margins are more rare, occur when an oceanic plate and a continental plate are moving parallel to each other in opposite directions. These transform margins are characterized by many offshore faults, which causes high degree of relief offshore, marked by islands, shallow banks, deep basins; this is known as the continental borderland. Passive margins are located in the interior of lithospheric plates, away from the plate boundaries, lack major tectonic activity, they face mid-ocean ridges. The East Coast of the United States is an example of a passive margin; these margins are less sloped than active margins. As continental crust weathers and erodes, it degrades into sands and clays. Many of these particles end up in streams and rivers that dump into the ocean. Of all the sediment in the stream load, 80% is trapped and dispersed on continental margins. While modern river sediment is still preserved closer to shore, continental shelves show high levels of glacial and relict sediments, deposited when sea level was lower.
Found on passive margins are several kilometers of sediment, consisting of terrigenous and carbonate deposits. These sediment reservoirs are useful in the study of paleoceanography and the original formation of ocean basins; these deposits are not well preserved on active margin shelves due to tectonic activity. Economically, the continental shelf is the most economically valuable part of the ocean, it is the most productive portion of the continental margin, as well as the most studied portion, due to its shallow, accessible depths. Due to the rise of offshore drilling and the limitations of fisheries off the continental shelf, the United Nations Convention on “Law of the Sea” was established; the edge of the continental margin is one criterion for the boundary of the internationally recognized claims to underwater resources by countries in the definition of the "continental shelf" by the United Nations Convention on the Law of the Sea. Such resources include fishing grounds and gas accumulations, sand and some heavy minerals in the shallower areas of the margin.
Metallic minerals resources are thought to be associated with certain active margins, of great value. Continent-ocean boundary
Media related to Wallaman Falls at Wikimedia Commons
