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St. Helena Seamount Chain
The St. Helena Seamount chain, also known as the St. Helena Seamounts, is an underwater chain of seamounts in the southern Atlantic Ocean. The chain has been formed by the movement of the African Plate over the Saint Helena hotspot The St. Helena hotspot is a volcanic hotspot located in the southern Atlantic Ocean. It is responsible for the island of St. Helena and the St. Helena Seamount chain. It is one of the oldest known hotspots on Earth, which began to produce basal .... References Geography of Saint Helena Seamount chains Seamounts of the Atlantic Ocean Geology of Saint Helena, Ascension and Tristan da Cunha . {{SaintHelena-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe and Asia from the "New World" of the Americas in the European perception of the World. The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, and North and South America to the west. As one component of the interconnected World Ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south (other definitions describe the Atlantic as extending southward to Antarctica). The Atlantic Ocean is divided in two parts, by the Equatorial Counter Current, with the North(ern) Atlantic Ocean and the South(ern) Atlantic Ocean split at about 8°N. Scientific explorations of the A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
African Plate
The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate to the west (separated by the Mid-Atlantic Ridge); the Arabian Plate and Somali Plate to the east; the Eurasian Plate, Aegean Sea Plate and Anatolian Plate to the north; and the Antarctic Plate to the south. Between and , the Somali Plate began rifting from the African Plate along the East African Rift. Since the continent of Africa consists of crust from both the African and the Somali plates, some literature refers to the African Plate as the Nubian Plate to distinguish it from the continent as a whole. Boundaries The western edge of the African Plate is a divergent boundary with the North American Plate to the north and the South American Plate to the south which forms the central and southern part of the Mid-Atlantic Ridge. The A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saint Helena Hotspot
The St. Helena hotspot is a volcanic hotspot located in the southern Atlantic Ocean. It is responsible for the island of St. Helena and the St. Helena Seamount chain. It is one of the oldest known hotspots on Earth, which began to produce basaltic lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ... about 145 million years ago. References Geography of Saint Helena Hotspots of the Atlantic Ocean Geology of Saint Helena, Ascension and Tristan da Cunha Volcanoes of Saint Helena Mid-Atlantic Ridge {{Volcanology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geography Of Saint Helena
Saint Helena is an island in the South Atlantic Ocean, about midway between South America and Africa. St Helena has a land area of 122 square kilometres and is part of the territory of Saint Helena, Ascension and Tristan da Cunha which includes Ascension Island and the island group of Tristan da Cunha. Physical geography Climate The climate of Saint Helena island can be described as tropical, marine and mild, tempered by the Benguela Current and trade winds which blow almost continuously. Similarly, the climate of Tristan da Cunha is marine, mild and also tempered by trade winds, although the climate is temperate in nature. Ascension Island is warmer and wetter than St Helena. Terrain Saint Helena has a rugged, volcanic terrain, with small scattered plateaus and plains, with the largest area of level ground on the island being Prosperous Bay Plain in the eastern arid area. The other islands of the group have a volcanic origin. The highest point on the island is Diana's Peak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount Chains
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamounts Of The Atlantic Ocean
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff, cliff-rock. Seamounts are typically formed from volcano#Extinct, extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanography, oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Saint Helena, Ascension And Tristan Da Cunha
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes of Earth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
