إڤرگليدز

Coordinates: 26°00′N 80°42′W / 26.0°N 80.7°W / 26.0; -80.7
هذه مقالة جيدة. لمزيد من المعلومات، اضغط هنا.
هذا المقال هو عن the natural region in Florida. إذا كنت تريد the national park، انظر Everglades National Park. إذا كنت تريد other uses، انظر إڤرگليدز (توضيح).
"Florida Everglades" redirects here. It is not to be confused with Florida Everblades.
Southern third of the Florida Peninsula, showing the area managed by the South Florida Water Management District, Lake Okeechobee, the Everglades, Big Cypress National Preserve, the South Florida Metropolitan Area, the العشرة آلاف جزيرة وخليج فلوريدا.
The primary feature of the Everglades is the sawgrass prairie.

إڤرگليدز أو إفرجليدز Everglades مناطق مستنقعات تعد من أهم مناطق العالم وتغطي 7,112 كم² في الجزء الجنوبي من فلوريدا. تمتد الأفرجليدز جنوبًا من بحيرة أوكيتشوبي إلى خليج فلوريدا وخليج المكسيك.

ويتكون شمالي أفرجليدز من مرج مغطى بماء ضحل وعشب منشاري ينمو حتى ارتفاع 3,7م في بعض الأماكن. وتنمو أشجار السرو البسيط والشجر الكستنائي والسفرجل الهندي والشمعية والصفصاف على كتل من الأرض المرتفعة تُسمى جزر الشجرة وبالقرب من الساحل الجنوبي تتداخل الإفرجليدز في مستنقعات ذات ماء مالح وفي مستنقعات المنغروف الساحلية. وتعيش عدة أنواع من الحيوانات في الإفرجليدز. وهي تشمل القواطير والغزلان والأسماك والنمور والبجع والثعابين.

أصل الكلمة

This map made by the U.S. military shows the term "Everglades" was in use by 1857.


الجيولوجيا

The geology of South Florida, together with a warm, wet, subtropical/tropical climate, provides conditions well-suited for a large marshland ecosystem. Layers of porous and permeable limestone create water-bearing rock and soil that affect the climate, weather, and hydrology of South Florida.[1] The properties of the rock underneath the Everglades can be explained by the geologic history of the state. The crust underneath Florida was at one point part of the African region of the supercontinent Gondwana. About 300 million years ago, North America merged with Africa, connecting Florida with North America. Volcanic activity centered on the eastern side of Florida covered the prevalent sedimentary rock with igneous rock. Continental rifting began to separate North America from Gondwana about 180 million years ago.[2] When Florida was part of Africa, it was initially above water, but during the cooler Jurassic Period, the Florida Platform became a shallow marine environment in which sedimentary rocks were deposited. Through the Cretaceous Period, most of Florida remained a tropical sea floor of varying depths.[3] The peninsula has been covered by seawater at least seven times since the bedrock formed.[4]

الحجر الجيري وطبقات المياه الجوفية

Fluctuating sea levels compressed numerous layers of calcium carbonate, sand, and shells. The resulting permeable limestone formations that developed between 25 million and 70 million years ago created the Floridan aquifer, which serves as the main source of fresh water for the northern portion of Florida. However, this aquifer lies beneath thousands of feet of impermeable sedimentary rock from Lake Okeechobee to the southern tip of the peninsula.[5]

A satellite image of the Everglades, taken in March 2019
Limestone formations in South Florida. Source: U.S. Geological Survey

Five geologic formations form the surface of the southern portion of Florida: the Tamiami Formation, Caloosahatchee Formation, Anastasia Formation, Miami Limestone, and the Fort Thompson Formation. The Tamiami Formation is a compression of highly permeable light-colored fossiliferous sands and pockets of quartz, 150 أقدام (46 m) thick. It is named for the Tamiami Trail that follows the upper bedrock of the Big Cypress Swamp, and underlies the southern portion of the Everglades. Between the Tamiami Formation and Lake Okeechobee is the Caloosahatchee Formation, named for the river over it. Much less permeable, this formation is highly calcitic and is composed of sandy shell marl, clay, and sand. Water underneath the Caloosahatchee Formation is typically very mineralized. Both the Tamiami and Caloosahatchee Formations developed during the Pliocene Epoch.[6][7]

Surrounding the southern part of Lake Okeechobee is the Fort Thompson Formation, made of dense, hard limestone, shells, and sand. Rain water is less likely to erode the limestone to form solution holes—smaller versions of sinkholes that do not intersect with the water table. In this formation the beds are generally impermeable.[8] Underneath the metropolitan areas of Palm Beach County is the Anastasia Formation, composed of shelly limestone, coquina, and sand representing a former mangrove or salt marsh. The Anastasia Formation is much more permeable and filled with pocks and solution holes.[8] The Fort Thompson and Anastasia Formations, and Miami Limestone and (x), were formed during the Sangamonian interglacial period.[9]

The geologic formations that have the most influence on the Everglades are the Miami Limestone and the Fort Thompson Formation. The Miami Limestone has two facies. The Miami Oolite facies, which underlies the Atlantic Coastal Ridge from southern Palm Beach County to southern Miami-Dade County, is made up of ooids: tiny formations of egg-shaped concentric shells and calcium carbonate, formed around a single grain of sand or shell fragment. The other facies, which underlies the eastern lower Everglades (in Miami-Dade County and part of Monroe County) consists of fossilized bryozoan organisms.[10] The unique structure was some of the first material used in housing in early 20th-century South Florida. The composition of this sedimentary formation affects the hydrology, plant life, and wildlife above it: the rock is especially porous and stores water during the dry season in the Everglades, and its chemical composition determines the vegetation prevalent in the region. The Miami Oolite facies also acts to impede flow of water from the Everglades to the ocean between Fort Lauderdale and Coot Bay (near Cape Sable).[11]

The metropolitan areas of Miami, Fort Lauderdale, and West Palm Beach are located on a rise in elevation along the eastern coast of Florida, called the Miami Rock Ridge, a relict oolite shoal deposited on top of the Anastasia Formation.[12] Along the western border of the Big Cypress Swamp is the Immokolee Ridge (or Immokolee Rise), a slight rise of compressed sand that divides the runoff between the Caloosahatchee River and The Big Cypress.[13] This slight rise in elevation on both sides of the Everglades creates a basin, and forces water that overflows Lake Okeechobee to creep toward the southwest.[14] Under both the Miami Limestone formation and the Fort Thompson limestone lies the Biscayne Aquifer, a surface aquifer that serves as the Miami metropolitan area's fresh water source. Rainfall and stored water in the Everglades replenish the Biscayne Aquifer directly.[9]

With the rise of sea levels that occurred during the Pleistocene approximately 17,000 years ago, the runoff of water from Lake Okeechobee slowed and created the vast marshland that is now known as the Everglades. Slower runoff also created an accumulation of almost 18 أقدام (5.5 m) of peat in the area. The presence of such peat deposits, dated to about 5,000 years ago, is evidence that widespread flooding had occurred by then.[15]

هيدرولوجيا

Predevelopment flow direction of water from Lake Okeechobee to Florida Bay Source: U.S. Geological Survey

The consistent Everglades flooding is fed by the extensive Kissimmee, Caloosahatchee, Miami, Myakka, and Peace Rivers in central Florida. The Kissimmee River is a broad floodplain that empties directly into Lake Okeechobee, which at 730 ميل مربع (1،900 km2) with an average depth of 9 أقدام (2.7 m), is a vast but shallow lake.[16] Soil deposits in the Everglades basin indicate that peat is deposited where the land is flooded consistently throughout the year. Calcium deposits are left behind when flooding is shorter. The deposits occur in areas where water rises and falls depending on rainfall, as opposed to water being stored in the rock from one year to the next. Calcium deposits are present where more limestone is exposed.[17]

The area from Orlando to the tip of the Florida peninsula was at one point a single drainage unit. When rainfall exceeded the capacity of Lake Okeechobee and the Kissimmee River floodplain, it spilled over and flowed in a southwestern direction to empty into Florida Bay. Prior to urban and agricultural development in Florida, the Everglades began at the southern edge of Lake Okeechobee and flowed for approximately 100 ميل (160 km), emptying into the Gulf of Mexico. The limestone shelf is wide and slightly angled instead of having a narrow, deep channel characteristic of most rivers. The vertical gradient from Lake Okeechobee to Florida Bay is about 2 بوصات (5.1 cm) per mile, creating an almost 60-ميل (97 km) wide expanse of river that travels about واحد من اثنان ميل (0.80 km) a day.[18] This slow movement of a broad, shallow river is known as sheetflow, and gives the Everglades its nickname, River of Grass. Water leaving Lake Okeechobee may require months or years to reach its final destination, Florida Bay. The sheetflow travels so slowly that water is typically stored from one wet season to the next in the porous limestone substrate. The ebb and flow of water has shaped the land and every ecosystem in South Florida throughout the Everglades' estimated 5,000 years of existence. The motion of water defines plant communities and how animals adapt to their habitats and food sources.[19]

المناخ

المستويات المتوسطة، القصوى، الدنيا لسقوط الأمطار على الساحل الشرقي لفلوريدا، من 1918 حتى 1985[20]
الفترة المتوسط الأقصى الأدنى
سنويا 51.9 بوصات (132 cm) 77.5 بوصات (197 cm) 36.7 بوصات (93 cm)
موسم المطر 34.5 بوصات (88 cm) 53.5 بوصات (136 cm) 23.4 بوصات (59 cm)
موسم الجفاف 17.4 بوصات (44 cm) 30.9 بوصات (78 cm) 7.3 بوصات (19 cm)

النظام البيئي

المقالة الرئيسية: جغرافيا وبيئة الإڤرگليدز
Major landscape types in the Everglades before human action. Source: U.S. Geological Survey


Tropical hardwood hammock

In a tropical hardwood hammock, trees are very dense and diverse.


أرض حبوب الصنوبر

A cross section of fresh water ecosystems in the Everglades, with relative average water depths


الصنوبر

A pond in The Big Cypress

القرم والبراري الساحلية

Red mangrove trees bordering a tidal estuary in the Everglades

خليج فلوريدا

A clump of mangroves in the distance, خليج فلوريدا في Flamingo


التاريخ

سمينول

Seminoles made their home in the Everglades

الاستكشاف

Map of the Everglades in 1856: Military action during the Seminole Wars improved understanding of the features of the Everglades
المقالة الرئيسية: Draining and development of the Everglades

نمو المناطق الحضرية

A canal lock in the Everglades Drainage District around 1915

وفي عام 1906م، بدأت ولاية فلوريدا في تجفيف مناطق الإفرجليدز لتجعل الوحل صالحًا للزراعة. وشُقت القنوات من بحيرة أوكيتشوبي في اتجاه جنوب شرقي المحيط. وزُرع قصب السكر والخضراوات، ولكن النار كانت تشتعل في السماد الحيواني بسهولة. وزحف الماء المالح من المحيط إلى الآبار ملوثاً الماء العذب. وبذل مجهود مقدر لحفظ الحياة الطبيعية للمنطقة، فجعلت حكومة الولايات المتحدة الجزء الجنوبي الغربي للإفرجليدز جزءًا من المتنزه القومي للإفرجليدز في عام 1947م.

وبالرغم من ذلك وعندما ازداد عدد سكان فلوريدا بخطى سريعة عند نهاية الحرب العالمية الثانية في عام 1945م، ازدادت مشاكل ماء إفرجليدز سوءاً. وخلال الستينيات من القرن العشرين، حفرت فرقة مهندسي الجيش الأمريكي قنوات في نهر كيسيمي. والكيسيمي هو مصدر الماء العذب الرئيسي لبحيرة أوكيتشوبي والأراضي الرطبة إلى الجنوب. وهذه الإجراءات خفضت بحدة تدفق الماء إلى الإفرجليدز مسببة نتائج مأساوية للحياة البرية. كما أن التحضر الضخم على ساحل فلوريدا الجنوبي الشرقي أضاف إلى فقد الماء عبئًا وتسبب في نقص ماء الشرب. وعند ثمانينيات القرن العشرين المبكرة، وصل هذا النقص إلى درجة الأزمة.

واستجابة لهذه المشاكل، فإن حكومة فلوريدا بدأت بمساعدة حكومة الولايات المتحدة عام 1983م برامج لإنقاذ الإفرجليدز المعرضة للخطر، وتشمل أهداف هذا المجهود 1- إعادة الكيسيمي إلى قاع النهر الأصلي. 2- إعادة فيضانات أرض المستنقع المجفف لمساعدة أنواع النبات والحيوان المهددة. 3- إجراءات لحفظ أنواع الحياة البرية المهددة بالانقراض. ولقد حقق المشروع بعض هذه الأهداف.


انظر أيضا

الهوامش والمصادر

  1. ^ South Florida Water Management District (2002). "Everglades Information: Geology". The Living Everglades. South Florida Water Management District. Archived from the original on 2008-01-16. Retrieved 2008-03-15.
  2. ^ Lodge. p. 3.
  3. ^ Lodge, p. 4
  4. ^ Gleason, Patrick, Peter Stone, "Age, Origins, and Landscape Evolution of the Everglades Peatland" in Everglades: The Ecosystem and its Restoration, Steven Davis and John Ogden, eds. (1994), St. Lucie Press. ISBN 0-9634030-2-8
  5. ^ Lodge, pp. 6–7.
  6. ^ "Florida Geological Survey: Tamiami Formation". Florida Department of Environmental Protection. January 24, 2006. Retrieved 2008-04-29.
  7. ^ UF & USDA (1948), p. 26–30.
  8. ^ أ ب UF & USDA (1948), p. 30–33.
  9. ^ أ ب Lodge, p. 10
  10. ^ "Virtual Field Trip of Selected Exposures of the Miami Limestone". www.geosciences.fau.edu. Research Labs : Florida Atlantic University – Department of Geosciences. Retrieved May 15, 2019.
  11. ^ Ginsburg, Robert (March 1953). "Surface Rock in the Lower Everglades". Everglades Natural History. Everglades Natural History Association. 1 (1): 21–24. Archived from the original on 2005-05-03. Retrieved 2008-03-17.
  12. ^ White, William A. (1970). The Geomorphology of the Florida Peninsula (Geological Bulletin 51). Florida Bureau of Geology. pp. 58–59. Archived from the original. You must specify the date the archive was made using the |archivedate= parameter. https://ufdc.ufl.edu/UF00000149/00001/images. 
  13. ^ U.S. Geological Survey (2004). "Environmental Setting – The Natural System: Watersheds and Coastal Waters (Big Cypress Watershed)". Circular 1134: The South Florida Environment – A Region Under Stress. U.S. Department of the Interior. Archived from the original on May 15, 2009. Retrieved 2008-03-17.
  14. ^ Duke University Wetland Center. "Historic Everglades Basin Topography". Everglades Field Trip. Duke University. Retrieved 2008-03-15.
  15. ^ U.S. Geological Survey (2004). "Environmental Setting – The Natural System: Geology". Circular 1134: The South Florida Environment – A Region Under Stress. U.S. Department of the Interior. Retrieved 2008-03-15.[dead link]
  16. ^ South Florida Water Management District (2008). "Lake Okeechobee & Region". U.S. Department of the Interior. Retrieved 2008-07-21.
  17. ^ U.S. Geological Survey (2004). "Environmental Setting – The Natural System: Hydrology". Circular 1134: The South Florida Environment – A Region Under Stress. U.S. Department of the Interior. Retrieved 2008-03-15.[dead link]
  18. ^ Fling, H.; N. Aumen; T. Armentano; F. Mazzotti (December 2004). "The Role of Flow in the Everglades Landscape". Circular 1452. University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS). Retrieved 2008-03-15.
  19. ^ U.S. Geological Survey (2004). "Environmental Setting – The Natural System: Watersheds and Coastal Waters". Circular 1134: The South Florida Environment – A Region Under Stress. U.S. Department of the Interior. Retrieved 2008-03-15.[dead link]
  20. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة usgs climate

قائمة المراجع

  • Barnett, Cynthia (2007). Mirage: Florida and the Vanishing Water of the Eastern U.S., University of Michigan Press. ISBN 0472115634
  • Carter, W. Hodding (2004). Stolen Water: Saving the Everglades from its Friends, Foes, and Florida, Atria Books. ISBN 0743474074
  • Caulfield, Patricia (1970) Everglades, Sierra Club / Ballantine Books. ISBN 345023536395
  • Douglas, Marjory S. (1947). The Everglades: River of Grass. R. Bemis Publishing. ISBN 0912451440
  • Douglas, Marjory; Rothchild, John (1987). Marjory Stoneman Douglas: Voice of the River. Pineapple Press. ISBN 0910923941
  • George, Jean (1972). Everglades Wildguide. National Park Service. Gov. doc #I 29.62:Ev2
  • Griffin, John (2002). Archeology of the Everglades. University Press of Florida. ISBN 0813025583
  • Grunwald, Michael (2006). The Swamp: The Everglades, Florida, and the Politics of Paradise. New York: Simon & Schuster. ISBN 0743251075
  • Hann, John (ed.) (1991). Missions to the Calusa. University Press of Florida. ISBN 0813019664
  • Jewell, Susan (1993). Exploring Wild South Florida: A Guide to Finding the Natural Areas and Wildlife of the Everglades and Florida Keys, Pineapple Press, Inc. ISBN 1561640239
  • Lodge, Thomas E. (2005). The Everglades Handbook. Understanding the Ecosystem. CRC Press. ISBN 1884015069
  • McCally, David (1999). The Everglades: An Environmental History. University Press of Florida. ISBN 0813023025
  • Ripple, Jeff (1992). Big Cypress Swamp and the Ten Thousand Islands: Eastern America's Last Great Wilderness, University of South Carolina Press. ISBN 0872498425
  • Tebeau, Charlton (1968). Man in the Everglades: 2000 Years of Human History in the Everglades National Park. University of Miami Press.
  • Toops, Connie (1998). The Florida Everglades. Voyageur Press. ISBN 0896583724
  • U.S. Army Corps of Engineers and South Florida Water Management District (April 1999). "Summary", Central and Southern Florida Project Comprehensive Review Study.
  • University of Florida Agricultural Experiment Station and United States Department of Agriculture Soil Conservation Service (March 1948). Bulletin 442: Soils, Geology, and Water Control in the Everglades Region.
  • Whitney, Ellie et al., eds. (2004) Priceless Florida: Natural Ecosystems and Native Species. Pineapple Press, Inc. ISBN 9781561643097

وصلات خارجية

الجغرافيا والبيئة
التاريخ
الحفاظ
الإعلام

26°00′N 80°42′W / 26.0°N 80.7°W / 26.0; -80.7

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