This is referred to as a fining upward sequence. In a regressive sequence, the reverse occurs, and it is called a coarsening upward sequence. The sequence coarsens upward in a regressive sequence because, as the sea level retreats, beach sand is deposited on top of the mud deposits associated with offshore marine environments.
The transgressive sequence is the reverse because the grains get finer as old beach deposits become buried and overlain by marine mud and silt as the sea level rises. Both sequences are common along the margins of seas and can indicate the presence of ancient seas as well as lakes. Sometimes, when sea level drops, irregularities in topography can create landlocked remnant seas, essentially giant lakes.
If conditions are especially dry, a landlocked sea will start to evaporate leaving behind salt and other mineral deposits. This happened to the Mediterranean Sea 5. Different minerals will be deposited depending on how much of the water has been evaporated. As a result, salt deposits can indicate the presence of an ancient sea that has long since evaporated.
A gulf is a type of bay, a body of water mostly enclosed by land with a strait connecting it to a larger body of water such as a sea or ocean. Gulfs are distinct from other types of bays in that they are generally very large in comparison. Gulfs often form when tectonic activity creates continental basins on the margins of oceans, seas, or large lakes that become flooded with water when sea or water level rises.
The Persian Gulf is an example of a gulf which may have once been dry land that became inundated as the sea level rose. Many gulfs were also created as the supercontinent Pangaea broke up to create the modern coastlines of eastern North and South America and western Europe and Africa. Many gulfs adjacent to rivers generally become filled with terrigenous sediment, creating large accumulations of mud, silt, and sand which can become submarine fans which are enormous deposits of sediment with a characteristic radiating fan shape.
The Bay of Bengal has a submarine fan of sediment emptying out of the Ganges River that is one of the largest submarine fans in the world. Gulfs that do not have large amounts of terrigenous sediment being carried into them can contain large carbonate deposits. Seas and gulfs are both bodies of water that are partially enclosed by land. They also can both form from terrestrial basins becoming filled with ocean water as the sea level rises. Additionally, they both can receive large amounts of sediment from deltas and those that contain less siliciclastic sediment from deltas will contain more carbonate rocks and sediments.
Though for many years there were only four known oceans, in , the International Hydrographic Organization added the Southern Ocean to the list. Oceanographers divide the ocean into different zones depending on the present physical and biological conditions. The oceans are further categorized into zones by depth, light and other factors.
The various different zones include pelagic zone all open oceans regions , photic zone surface to meters down and aphotic zone depths exceeding meters. The depth of an ocean ranges from 20, feet to 36, feet.
The ocean currents also play a bit part in the Earth climate, by transferring heat from the tropics to the polar regions, and transferring warm or cold air and precipitation to coastal regions, where winds may carry them inland. A gulf is a part of the ocean and is a large area of an ocean of a sea that is enclosed by land partially or on three sides.
World View. More From Reference. What Is a Map Key? How Many U. Taxpayers Are There? Humans use the sea and gulf in different forms as the sea can be used for industrial purposes while the gulf can be used for a harbor. Sea is the shallow saltwater body that is in some way fragmented off from the larger ocean by a bunch of land such as an island. It can also be engulfed continental basin and isolated from the ocean. Sea is found on the edge of the ocean and partially enclosed by land. A gulf is defined as a body of water enclosed by land connecting it to a larger body of water such as ocean or sea.
It is the part of a sea that deeply penetrates the land and is surrounded by land. It has a narrow opening or looks like a narrow, deep inlet of the sea. Sea is the saltwater body that is parted off from the ocean; it is sometimes enclosed by land. Sea is smaller than an ocean and is usually located where the land and ocean meet.
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