A river delta is a landform created by deposition of sediment, carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, estuary, reservoir, or another river that cannot carry away the supplied sediment; the size and shape of a delta is controlled by the balance between watershed processes that supply sediment, receiving basin processes that redistribute and export that sediment. The size and location of the receiving basin plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers, they can impact drinking water supply. They are ecologically important, with different species' assemblages depending on their landscape position. River deltas form when a river carrying sediment reaches either a body of water, such as a lake, ocean, or reservoir, another river that cannot remove the sediment enough to stop delta formation, or an inland region where the water spreads out and deposits sediments.
The tidal currents cannot be too strong, as sediment would wash out into the water body faster than the river deposits it. The river must carry enough sediment to layer into deltas over time; the river's velocity decreases causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta; when the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment; as a result, sediment drops out of deposits. Over time, this single channel builds a deltaic lobe; as the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation. As the slope of the river channel decreases, it becomes unstable for two reasons. First, gravity makes the water flow in the most direct course downslope. If the river breaches its natural levees, it spills out into a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope.
Second, as its slope gets lower, the amount of shear stress on the bed decreases, which results in the deposition of sediment within the channel and a rise in the channel bed relative to the floodplain. This makes it easier for the river to breach its levees and cut a new channel that enters the body of standing water at a steeper slope; when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network. Another way these distributary networks form is from the deposition of mouth bars; when this mid-channel bar is deposited at the mouth of a river, the flow is routed around it. This results in additional deposition on the upstream end of the mouth-bar, which splits the river into two distributary channels. A good example of the result of this process is the Wax Lake Delta. In both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition.
This results in the smoothing of the planform shape of the delta as the channels move across its surface and deposit sediment. Because the sediment is laid down in this fashion, the shape of these deltas approximates a fan; the more the flow changes course, the shape develops as closer to an ideal fan, because more rapid changes in channel position resultsf in more uniform deposition of sediment on the delta front. The Mississippi and Ural River deltas, with their bird's-feet, are examples of rivers that do not avulse enough to form a symmetrical fan shape. Alluvial fan deltas, as seen by their name and more approximate an ideal fan shape. Most large river deltas discharge to intra-cratonic basins on the trailing edges of passive margins due to the majority of large rivers such as the Mississippi, Amazon, Ganges and Yangtze discharging along passive continental margins; this phenomenon is due to three big factors: topography, basin area, basin elevation. Topography along passive margins tend to be more gradual and widespread over a greater area enabling sediment to pile up and accumulate over time to form large river deltas.
Topography along active margins tend to be steeper and less widespread, which results in sediments not having the ability to pile up and accumulate due to the sediment traveling into a steep subduction trench rather than a shallow continental shelf. There are many other smaller factors that could explain why the majority of river deltas form along passive margins rather than active margins. Along active margins, orogenic sequences cause tectonic activity to form over-steepened slopes, brecciated rocks, volcanic activity resulting in delta formation to exist closer to the sediment source; when sediment does not travel far from the source, sediments that build up are coarser grained and more loosely consolidated, therefore making delta formation more difficult. Tectonic activity on active margins causes the formation of river deltas to form closer to the sediment source which may affect channel avulsion, delta lobe switching, auto cyclicity. Active margin river deltas tend to be much smaller and less abundant but may transport similar amounts of sediment.
However, the sediment is never piled up in thick sequences due to the sediment traveling and depositing i
The United States Air Force's 226th Combat Communications Group is a combat communications headquarters unit located at Abston Air National Guard Station in Montgomery, Alabama, USA. The Group is one of two Air National Guard Combat Communications Groups nationwide, which together constitute over 60% of the U. S. Air Force's tactical communications capability; the 226 CCG is one of three major organizations. The mission of the 226th Combat Communications Group is to command, equip and administer assigned and attached forces to ensure complete mission readiness in support of emergency USAF requirements, to provide timely and reliable communications and engineering and installation in support of state emergencies; the 226 CCG was organized on 18 June 1954 as part of the 225th Radio Relay Squadron. The 225th was organized in March 1953 in Greenville, Mississippi, as part of the Mississippi Air National Guard; the unit was formally organized on 18 June 1954, was transferred to the Alabama Air National Guard and relocated to Gadsden.
On 22 February 1971, an element of the 225th was reorganized as the Headquarters, 226th Mobile Communications Group and allotted to the National Guard Bureau. The unit received federal recognition on 29 September 1971. In 1986, the 226th was renamed; the group headquarters moved to Abston Air National Guard Station in February 1996. The 226th gained seven additional squadrons on 1 October 2013, when the 281st Combat Communications Group was inactivated. Constituted as the 226th Mobile Communications Group and allotted to the Air National Guard on 22 February 1971Federally recognized on 13 September 1971 Redesignated 226th Combat Communications Group on 1 April 1976 Redesignated 226th Combat Information Systems Group on 1 July 1985 Redesignated 226th Combat Communications Group on 1 October 1986 Major Command/Gaining CommandAir National Guard/Air Force Communications Service Air National Guard/Air Combat Command Air National Guard/Air Force Space Command Currently assigned224th Joint Communications Support Squadron - Brunswick, Georgia 232d Combat Communications Squadron – Abston ANGS, Alabama 263d Combat Communications Squadron - New London ANGS, New London, North Carolina 265th Combat Communications Squadron - South Portland ANGS, South Portland, Maine 267th Combat Communications Squadron - Joint Base Cape Cod, Massachusetts 269th Combat Communications Squadron - Springfield ANGS, Ohio 271st Combat Communications Squadron - Fort Indiantown Gap, Pennsylvania 280th Special Operations Communications Squadron - Dothan Regional Airport ANGS, Alabama 282d Combat Communications Squadron - North Smithfield ANGS, North Smithfield, Rhode Island 283d Combat Communications Squadron - Dobbins ARB, Georgia 290th Joint Communications Support Squadron - MacDill AFB, FloridaPreviously assigned114th Combat Communications Squadron - Patrick AFB, Florida 115th Air Control Squadron - Dothan, Alabama 225th Combat Communications Squadron - Gadsden, Alabama 228th Combat Communications Squadron - McGhee-Tyson ANGB, Tennessee 240th Combat Communications Squadron - McEntire ANGB, South Carolina 241st Engineering Installation Squadron - Chattanooga, Tennessee 245th Air Traffic Control Squadron - McEntire ANGB, South Carolina 285th Combat Communications Squadron - St. Croix, U.
S. Virgin Islands Martin Air National Guard Station, Alabama, 13 September 1971 Abston Air National Guard Station, Alabama, February 1996 – present Air Force Outstanding Unit Award 1 January 1976 – 31 December 1977 1 January 1989 – 31 December 1989 1 January 1990 – 31 December 1990 1 January 1991 – 31 December 1991 1 January 1996 – 31 December 1997 Explanatory notes Citations Alabama ANG: 187th Fighter Wing
The Anti-Slavery Society was the everyday name of two different British organisations. The first was committed to the abolition of slavery in the British Empire, its official name was the Society for the Mitigation and Gradual Abolition of Slavery Throughout the British Dominions. This objective was achieved in 1838 under the terms of the Slavery Abolition Act 1833. A successor organisation, the British and Foreign Anti-Slavery Society, was formed in 1839 to fight for global abolition. After the end of slavery in the United States, the British organisation re-focussed. Through mergers and name changes, it is now known as Anti-Slavery International; the elimination of slavery throughout the world was in the mind of early abolitionists. The committee which established the Society for Effecting the Abolition of the Slave Trade in 1787 campaigned for an end to the transatlantic slave trade from Western Africa to the New World, a trade dominated by Britain; the Slave Trade Act 1807 made the trade illegal in the British Empire, but brought no change to the condition of enslaved people.
Following this, British abolitionists turned their attention to abolishing slavery itself, first in British colonies, in the US and the colonies of other European powers, in parts of the world where it had long been legal, such as in the Middle East and China. The first British organisation to refer to itself as the Anti-Slavery Society began in 1823. Founding members included Thomas Clarkson, its official name was the Society for the Mitigation and Gradual Abolition of Slavery Throughout the British Dominions. Its work included supporting the first slave narrative to be published by a Black woman, Mary Prince, The History of Mary Prince, A West Indian Slave; the publishers were sued by the family. The book was much sought after. A wide range of views emerged among the members. Broadly, there were abolitionists who insisted on the full working out of the gradual process of abolition and amelioration, the younger, more radical members, whose moral outlook regarded slavery as a mortal sin to be ended forthwith.
Elizabeth Heyrick's 1824 pamphlet "Immediate, not Abolition" gave the tone to the argument. The latter group, including Joseph Sturge and many others, publicly campaigned throughout Britain; the idea was to engender public pressure for a new parliamentary act to outlaw slavery, rather than continue the gradualism of Whitehall's negotiations with colonial governments. In 1831 George Stephen and Joseph Sturge formed a ginger group within the Anti-Slavery Society, the Agency Committee, to campaign for this new act of Parliament; this campaign, public pressure, led to the Slavery Abolition Act of 1833, though it contained compromises which they disliked. Jamaican mixed-race campaigners such as Louis Celeste Lecesne and Richard Hill were members of the Anti-Slavery Society; the indentured labour schemes were opposed by Sturge and the Agency Committee. In response to the new legislation, other members of the Anti-Slavery Society considered their work over; the original purpose, as reflected in the name of the society, they thought, been achieved.
With abolition of slavery throughout the British dominions achieved, British abolitionists in the Agency Committee of the Anti-Slavery Society considered that a successor organisation was needed to tackle slavery worldwide. Under the guidance of Joseph Sturge, the committee duly formed a new society and Foreign Anti-Slavery Society on 17 April 1839, it became known as the Anti-Slavery Society, as had the earlier society. The first secretary was John Harfield Tredgold, the first treasurer, George William Alexander of Stoke Newington. Along with the founding committee, which included the Anglican Thomas Fowell Buxton, the Quaker William Allen, the Congregationalist Josiah Conder, they organised the first World Anti-Slavery Convention in London in 1840. Thomas Clarkson was the key speaker, the Convention attracted people from nations around the world where slavery was practiced. In 1944, a Journalist James Ewing Ritchie issued a paper to the society on sugar slavery; the convention had been advertised as a "whole world" convention, but the delegates representing anti-slavery societies in the United States included several women, among them Lucretia Mott and Elizabeth Cady Stanton, who were instrumental in the movement for women's rights.
Convention leaders refused to seat the women delegates from America, prominent male abolitionists such as Thomas Knight were outraged. He went on to form his own society. In the 1850s, under Louis Chamerovzow, the society helped John Brown write and publish his autobiography a decade before the American Civil War ended slavery in the United States; the second secretary of the Anti-Slavery Society, appointed under the honorary secretaries Joseph Cooper and Edmund Sturge, was the Rev. Aaron Buzacott, the son of a South Seas missionary named Aaron Buzacott. With American slavery abolished in 1865, Buzacott worked with Joseph Cooper in researching and publishing work designed to help abolish slavery in elsewhere in the Middle East and Africa. In 1909, the society merged with the Aborigines' Protection Society to form the Anti-Slavery and Aborigines' Protection Society, whose prominent member was Kathleen Simon, Viscountess Simon. In 1990 the name was chan