Jura Mountains

The Jura Mountains are a chain of geological elevations, whose highest peak reaches 1,723 m (5654 ft). They run from northeast to southwest for about 250 km, forming a wide open arch that constitutes the natural border between France and Switzerland. Thus, they are located in west-central Europe, between the Rhine and Rhône River. Le Crêt de la Neige, the highest peak,  is situated in the department of Ain, France.

Geology

The Jura Mountains gave the name to a period of the Mesozoic Era; the Jurassic, which followed the Triassic and preceded the Cretaceous. Hence, these low mountain range is about 160 million years old. Lime is the main rock that makes up the bulk of the system.

The Jura Mountains originated from the thin-skinned tectonic that deformed a calcareous Mesozoic cover. Although the Mesozoic Jura shelf emerged at the end of the Cretaceous, the rock structure, which is lime, was formed and compressed during the Jurassic. Later, during the Cenozoic Era, it underwent Paleogene subtropical weathering and erosion. During the late Miocene epoch (Tertiary period of Cenozoic), it was invaded by a perialpine sea. Then the internal part of the Jura Mountain would be reached by Alpine compression.

The intense folding of the internal Jura was responsible for a thickened cover, which in turn induced the uplift of this zone. Most of the fold belt of the Jura is no longer active today, according to present day stress field pattern; this was suggested by Becker in 1999.

Below, map of Europe, showing the exact location of the Juran Mountains.


 

Pacific Ring of Fire

The Pacific ring of fire is the geological boundary line which surrounds the Pacific tectonic plate. Its the limit is where it meets other plates, or drifts apart from them. Thus, on its southern border the line divides it from the Antarctic plate; on its eastern side, the line separates it from the Nazca, Cocos and North American plate; on the north, this geological fissure divides it also from the North American plate, while on its western border, the Pacific plate runs into the Philippine and Australian plate; here the fissure shows intense geological activities, causing strong earthquakes and tsunamis. This is due to the collision of these tectonic plates.

The coastal regions of California are on the Pacific ring of fire. So is Japan, the Philippine islands, New Guinea, and New Zealand. When the Pacific plate edge suddenly and violently slips under the Philippine or the Australian plate, powerful earthquakes hit cities lying near this geological boundary line. The strong earthquake that struck Japan on March 11, 2011, caused an apocalyptic tsunami that killed thousands of people and affected a nuclear power plant. Thus, these violent natural phenomena are caused by what is known as the Pacific ring of fire. In other places, the volcanic activities spew out lava deep on the bottom of the ocean as the molten rocks pile up and forms islets, which over the millions of years they become islands.

Below, the different tectonic plates whose boundaries form the Pacific Ring of Fire.


 

South Africa Topography

South Africa topography basically consists of a broad central plateau, which is surrounded by a series of escarpments on its west, south, and east side. These surrounding high, steep slopes are called the Great Escarpment. Inland from the crest of the Great Escarpment, the landscape is composed of rolling grassy plains, which gradually descend to an average altitude of about 900 m (2,952 ft) in the center. The Highveld is the highest and largest grassland region of the central plateau.

The outside the central plateau, the periphery of the escarpment consists of overlooking slopes, which pitch to the eastern, southern, and western coasts. To the east of the central plateau, there is the Drakensberg Mountain Range. To the south, there is a series of three chains of mountains; the Great Karroo Range, the Groote-Swartberge, and the Little Karroo Range, which extends along near the southern coast of the country.

South Africa features a rugged coastline, with rocky shores, sheltering a few bays and harbors. There are coral reefs off the eastern coast that surround Sodwana Bay, which attracts divers from all over the world. Meanwhile, the country is crisscrossed by three main rivers; the Orange, the Vaal, and the Limpopo River. The Vaal is the most important tributary of the Orange River, which is 2,100-km-long, flowing in eastern-western direction as it empties into the Atlantic Ocean.

On the east, South Africa is bordered by the Indian Ocean; on the west by the Atlantic, and on the south by both the Indian and the Atlantic Ocean. The coastal belt of the west and south ranges in elevation between 150 and 180 m (500 to 600 ft). This strip of land is very fertile. In the East, on the other hand, there is very little coastal plain, where the Great Escarpment borders the central plateau as it reaches almost to the sea.

Below, a physical map of South Africa, showing the different geographical features of its topography.


 

Continental and Oceanic Crust

The continental and oceanic crust constitute the external surface of our planet. They are the outermost layer of the Earth as they are parts of the lithosphere. The crust is constantly being formed, destroyed and rebuilt by geological processes happening inside the mantle. It consists of volcanic rocks on top of which layers of softer sedimentary rock and organic sediment rest. On average, it is estimated that it is 22 miles (35 km) deep and it gets slightly thicker every year as more molten rocks constantly come out from within the Earth.

Continental Crust

It is the geological layer which is constituted by dry land. It is made up largely of rocks called granite, which is not only igneous (volcanic) but also plutonic rock. Granite is the pink, black, and grey rock that came out of active volcanoes hundreds of millions of years ago, cooling off and solidifying under the earth surface. It is characterized by being the hardest rock on Earth. Today, melted rocks from beneath this crust still rise to the surface through volcanic activities and tectonic plates movement as they solidify into granite rocks.

Oceanic Crust

It is the layer of geological material located under the oceans. It consists of rocks called basalts. They are black, dense heavy rocks, which were spewed out of underwater volcanoes. Although they are not easily spotted, there is a lot of them in the ocean floors. Oceanic crust is much younger than continental crust, because the former is constantly being destroyed and reshaped anew by these volcanoes, adding new rocks to it. Continental crust rocks are about 3.7 billion years old, whereas oceanic crust basalt is about 100 million years of age.

Tectonic Plates

The tectonic plates are rigid blocks of lithosphere which drift over the surface of the Earth. They move in different directions, separating from one plate to collide against another. The planet Earth’s crust is not one indivisible layer of rocks but it is broken up into large pieces, which are called plates. The movement of each one of these plates causes what is known as the continental drift. Their existence is based on the theory of plate tectonics, which dates back to the 1920s, when the German geophysicist, Alfred Wegener, first explained how a large original supercontinent broke up into smaller ones that drifted apart to take today’s present positions. If you take a look at the diagram/map below this article, you will have a clear picture of them.

Cause

The breaking up of the lithosphere into several drifting plates is caused by the immense inner pressure exerted by the mantle’s molten rocks that are squeezed upwards by convection currents. It means that the molten rocks flows in streams between the lower mantle and the upper mantle in a circulatory pattern. This, in turn, caused the formation of the different continents from a primeval continental mass. The molten rocks are ejected up in the form of lava onto the planet’s surface through what is known as subduction zone, which is the place where two tectonic plates meet, with one pushing against the other. This gives birth to mountain ranges and volcanoes.

Number of plates

Although the tectonic plates are separated from one another, they are held together by the upper mantle. When they move, each plate carries land mass and the ocean floor. The planet Earth has more than twelve different plates, with the exact number of them depends on where the geologists establish the plate boundaries. Most of the scientists agree that there are the following tectonic blocks: South American, Nazca, Cocos, Caribbean, North American, Pacific (the largest plate), Juan de Fuca, Australian, Eurosian, African, Somali, Anatolian, Aegean, Indian, Philippine, and Antarctic Plate. The Nazca Plate moves and pushes against the South American Plate, with a long subduction zone being the boundary, as this geological collision caused the folding and elevation of rocks and geological materials that shaped the Andes Mountain Range. African Plate collides against the Eurasian, the Aegean, and the Anatolian Plate.

Below, you can see a map of the Earth that show the different tectonic plates


 

Ocean Currents

Ocean currents are moving masses of sea water, which flows in all oceans, determining the weather patterns in coastal regions. Each one of them have a characteristic direction, length, depth, speed, and temperature. They move like great flow of global conveyor belts.

Ocean currents are caused by the planet rotation, the gravitation of the moon, the wind, temperature, and salinity differences. Warm ocean currents are corridors of warm water moving from the tropics towards poles where they release energy to the air. Cold ocean currents are corridors of cold water moving from higher latitudes toward the equator where they absorb the energy received in the tropics as they cool the air above.

Although some ocean currents result from density and salinity variations of water, the major ocean currents are wind-driven currents. Surface currents make up about 10% of all the water in the ocean. These waters are the upper 400 meters of the ocean. Deep water currents make up the other 90% of the ocean; these waters move around the ocean basins by density driven forces and gravity. Density difference is a function of different temperatures and salinity.

Ocean currents can flow for thousands of kilometers. They are very important in determining the climates of the continents, especially those regions bordering on the ocean. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is the Hawaiian Islands, where the climate is cooler than the tropical latitudes in which they are located because of the California Current.

Below, a world map showing the cold and war ocean currents.


 

Orinoco River

The Orinoco River is the longest and most important river of Venezuela. It is 1,550-mile (2,500 km) long. It rises on the western slopes of the Parima mountains in the southwestern Guiana Highlands. Then it flows down in a southeast-northwest direction, to the green lowlands of Venezuela. Next, it turns right to run eastward across the savannas, making a large arc. It contains more than 1,000 species of fish, which include piranha. Giant otters and crocodiles are also found in its waters.

The Orinoco River empties into the Atlantic Ocean, forming a delta. Along its way, it receives fresh water from important tributaries, such as the Ventuari, Caura, and Caroni river from the right, and the Guaviari, Meta, Apure, and Arauca river from the left. Thus, the Orinoco becomes very wide, between 1 and 1.5 km in width. It is formed by 90% of rain water and only 10% of melting snow. The melting snow water flows from the Andes Mountain Range through the Apure and Guaviare river.

Below, a map of Venezuela, exhibiting the Orinoco River, which runs across the South American country.


 

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