There are many symptoms of relief on earth. Three classes have been made of them. Continents and oceans come in the relief features of the first order. The relief features of the second order include mountains, plains, and plateaus, which are formed by the internal movements of the earth and exogenous waters. The relief features of the third order include valleys, hills, deltas, and glaciers, which are formed only by the forces of erosion, such as flowing water, wind, waves, etc.
- Explain the meaning of Physical Geography. Explain its Scope and Importance.
- Discuss the nature and Scope of Geomorphology.
The two main forms of the Earth’s surface are considered to be continents and oceans. There are some characteristics of the distribution of these two forms of crust, which help solve the problems present about their origin. When and how the continents and oceans originated, is undoubtedly a complex and controversial subject, about which many scholars have expressed their views. The following features of the distribution of continents and oceans are visible from the study of the globe.
- Most of the continents are in the Northern Hemisphere and the oceans are in the Southern Hemisphere, but the opposite is the case in the pole regions. There are oceans near the North Pole and continents near the South Pole.
Land Hemisphere covers 81 percent of the land, whose pole lies in Brittany and under which some part of North America, Europe, Asia, Africa, and South America comes. On the contrary, water is more important in the water hemisphere whose pole point lies around New Zealand. The shape of the continents becomes wider towards the north and narrower and sharper towards the south. This is less applicable in the case of Australia. Similarly, the oceans narrow towards the north and widen towards the south.
The anti-diameter relationship of water and land on the surface is also a feature of its distribution. Sea is behind the sea in 46.6 percent of the surface, but only 1.4 percent is land behind the land. 5 percent of the land is behind the sea.
The interior of the Earth is still warm and is slowly cooling down. Based on this assumption, the British mathematician Lothian Green presented his tetrahedral hypothesis. The said scholar has considered the distribution of continents and oceans as a tetrahedron, around which the flows in three directions. Surrounded by four figures of equal sides.
The shape of the tetrahedron is clear from the picture, in which three flattened parts of the shape of an isosceles triangle are visible, which gives the impression of the North Atlantic Ocean and the Indian Ocean, but the fourth flat part is invisible in the figure, from which the Pacific Ocean is displayed, But the raised parts of this figure, which indicate the sides of the triangular flattened parts. Describes the position of the continents.
According to Lithian Green, the effect of pressure on any round soft object changes its shape to that of a tetrahedron. He assumed that with the cooling of the earth, the inner part of the earth contracted faster than the outer part, that is, the volume of the inner part decreased.
The upper surface was already solid and hard, so it could not shrink, causing a difference between the inner and outer layers of the Earth. In such a state, one has to come in the shape of the earth, whose volume is small even though the surface is large. In the opinion of scholars, such a shape can only be quadrilateral.
If the area of the sphere and the tetrahedron are equal, then the volume of the quaternary will be less than the volume of the sphere.
According to this belief, the earth has not yet reached the shape of a perfect tetrahedral, but as it is getting colder, the shape of the tetrahedral is getting complete. Due to the effect of the force of attraction, the upper crust settled in the shape of the inner tetrahedron, which gave rise to the oceans and continents. Due to the shrinking of the inner parts, the troughs formed by the uneven inward sinking of the outer layers formed the sea parts which corresponded to the flat surface of the tetrahedral. corresponded to the corners and sides of the continent.
Combining this idea with the above figure, it is known to be correct because if the tetrahedron is immersed in a globe of water, then the water will come on the sticky part soon, but the raised part will remain outside the water, which respectively points to the sea and land. Huh. Even if the earth is considered to be the base of the tetrahedron, then part of its edges and corners will force them to sit down and rise and an attractive revolving earth will be formed.
The following are the criticisms made by various scholars, this idea was recognized for a long time, but it started getting criticized in the last century. Scientists say that the shape of the rotating Earth cannot remain as a tetrahedron because it is not a balanced shape.
At the same time, it is also unusual for the earth to assume the form of a tetrahedral by a round body due to the high speed of the moving earth. According to the principle of the tetrahedron, the most terrestrial part should be at 300 N latitude. • ButThe terrestrial portion is 80.1 percent at 600 30 latitudes and only 43.6 percent at 300 30 latitudes. The southern part of the continents should be at a distance of 1200, but in reality, this is not the case.
British scientist Gregory presented some geographical conditions of the surface in confirmation of this hypothesis.
In the northern hemisphere, the part of the land is more, the shape of most of the geographical objects is triangular, the parts of the land protruding towards the south, the seas are getting narrower towards the north and the anti-diameter relationship between the sea and the land parts is the tetrahedron by the said scholar. The result of the shape of.
Apart from this, the continents of Asia and North America meet each other by making an angle of 1200 and there is an external angle formed on the sides of the tetrahedron.
The German geologist Suisse has considered the earth’s surface to be made up of two types of rocks. He has accepted some parts to be made of resistant rocks and the remaining part to be made of non-resistant rocks. Parts of hard rocks are old and hard and do not bend even after breaking.
In the Northern Hemisphere, such parts are found at three sites. In this, the first part of Laurasia includes the part of Canada located east of Raki and the western islands of Scotland. The second part is that of the Baltic Shield, which includes the regions around the Baltic Sea. The third part is called Angaraland and in this part of eastern Siberia and China falls. In the southern circle is the hard part of Gondwanaland, which includes Brazil, Africa, Arabia, the peninsulas of India, Hindi China, and the western plateau of Australia.
Due to the weak intermediate surface of these parts, it could not bear the heavy load and bends took place in it. There were equal turns in different periods. In the inner state of the times of turning, there was peace on the whole earth. Cracks developed in the upper parts of hard rocks, as a result of which large parts of the crust were submerged, which were formed due to the formation of oceans.
The Atlantic Ocean was formed by the breakup of Laurasia and Gondwanaland. In the middle of the hard parts of Asia, Europe, and Africa there was a part of soft rocks, in which before the third megalith there was a sea named Tethys, the remnants of which the Mediterranean Sea is still present and on which the pressure of many parts on both sides of Asia. And the new fold mountains of Europe were formed. According to this, continents were formed from the raised parts of hard and soft land while turning and due to the cracking, the submerged parts became oceans.