Shark Valley

Shark Valley is a geological depression at the head of the Shark River Slough in far western Miami-Dade County, Florida, United States. It is currently part of Everglades National Park. Shark Valley empties into Shark River in the Ten Thousand Islands of Monroe County. Shark Valley characteristically includes sawgrass prairie that floods during the rainy season, hence the name "river of grass"—Pa-Hay-Okee, from the Mikasuki language—for such marshes in the Everglades. Shark Valley features a Visitor Center with educational displays, a park video, an underwater camera and informational brochures. The entrance to Shark Valley is located along Tamiami Trail (US 41) near the Miami-Dade–Collier County line.

Characteristics

Shark Valley contains large expanses of oolitic limestone either exposed or overlain by marl. The area, having a brief hydroperiod, is seasonally submerged, with Cladium jamaicense (sawgrass) being the dominant vegetation. Unlike the deeper Shark River Slough, Shark Valley does not contain standing water year-round. Wildlife seen in Shark Valley includes alligators, ibis, wood storks, roseate spoonbills, raccoons, white-tailed deer, and various amphibians.

National park

A national park is a park in use for conservation purposes. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently, there is a common idea: the conservation of 'wild nature' for posterity and as a symbol of national pride. An international organization, the International Union for Conservation of Nature (IUCN), and its World Commission on Protected Areas, has defined "National Park" as its Category II type of protected areas.

While this type of national park had been proposed previously, the United States established the first "public park or pleasuring-ground for the benefit and enjoyment of the people", Yellowstone National Park, in 1872. Although Yellowstone was not officially termed a "national park" in its establishing law, it was always termed such in practice and is widely held to be the first and oldest national park in the world. The first area to use "national park" in its creation legislation was the US's Mackinac Island, in 1875. Australia's Royal National Park, established in 1879, was the world's third official national park. In 1895 ownership of Mackinac Island was transferred to the State of Michigan as a state park and national park status was consequently lost. As a result, Australia's Royal National Park is by some considerations the second oldest national park now in existence.

Everglades National Park

Everglades National Park is a U.S. National Park in Florida that protects the southern 20 percent of the original Everglades. In the United States, it is the largest tropical wilderness, the largest wilderness of any kind east of the Mississippi River, and is visited on average by one million people each year. It is the third-largest national park in the lower 48 states after Death Valley and Yellowstone. It has been declared an International Biosphere Reserve, a World Heritage Site, and a Wetland of International Importance, one of only three locations in the world to appear on all three lists.

Although most U.S. national parks preserve unique geographic features, Everglades National Park was the first created to protect a fragile ecosystem. The Everglades are a network of wetlands and forests fed by a river flowing .25 miles (0.40 km) per day out of Lake Okeechobee, southwest into Florida Bay. The Park is the most significant breeding ground for tropical wading birds in North America, contains the largest mangrove ecosystem in the western hemisphere, is home to 36 threatened or protected species including the Florida panther, the American crocodile, and the West Indian manatee, and supports 350 species of birds, 300 species of fresh and saltwater fish, 40 species of mammals, and 50 species of reptiles. The majority of South Florida's fresh water, which is stored in the Biscayne Aquifer, is recharged in the park.

Shark

Sharks are a group of fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago.Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole.

Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. Sharks are found in all seas and are common to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive and be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have several sets of replaceable teeth.

Valley

A valley is a low area between hills, often with a river running through it.

In geology, a valley or dale is a depression that is longer than it is wide. The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys. Most valleys belong to one of these two main types or a mixture of them, (at least) with respect to the cross section of the slopes or hillsides.

Valley terminology

A valley in its broadest geographic sense is also known as a dale. A valley through which a river runs may also be referred to as a vale. A small, secluded, and often wooded valley is known as a dell or in Scotland as a glen. A wide, flat valley through which a river runs is known in Scotland as a strath. A mountain cove is a small valley, closed at one or both ends, in the central or southern Appalachian Mountains which sometimes results from the erosion of a geologic window. A small valley surrounded by mountains or ridges is sometimes known as a hollow. A deep, narrow valley is known as a cwm (also spelled combe or coombe). Similar geological structures, such as canyons, ravines, gorges, gullies, and kloofs, are not usually referred to as valleys. See also: "chine". A valley formed by erosion is called an erosional valley; a valley formed by geologic events such as drop faults or the rise of highlands is called a structural valley.