Free Geology Question & Answer Sample

Continental drift is the theory which proposes that the world was originally made up of a single continent. With the passage of time, this continent was broken up, and it drifted apart to form the seven continents that are present today. It was proposed by Alfred Wegener whose hypothesis stands that the continents are made up of rocks that rest on the heavier weighing rocks on the crust, and this is a movement that is mimicked by icebergs on water. The continents move rigidly. Plate tectonics theory proposes that the Earth’s surface is actually broken up into a number of plates, which shift gradually from their place. The movement of the plates is in accordance with the heat under the Earth’s surface. These places move a few inches apart every year.
The first piece of evidence discovered by scientists was the similarly distributed fossil rocks which were found at considerable distances between land and oceans. It meant that if one fossil of a species was found in South America, then the same could be found in regions of Africa. The second evidence was the method in which the coastlines matched with one another. Fitting like the piece in a jigsaw puzzle, certain coastlines matched with those of others. The third evidence is paleomagnetism, which is the study of magnetism in the rocks, which was stimulated at the time they were formed. Studying their congruence and understanding their magnetic field let to this theory.
Magnetic anomalies occur in the ocean floor due to the varying magnetic strength of the Earth’s magnetic field. This magnetism is induced by the rocks present on the ocean floor. Usually, these anomalies form only about 1% of the total strength of magnetic field present in the earth. Since they are anomalies, they can be stronger or weaker, depending on where they occur. They also occur in a parallel manner which makes them stretch up to hundreds of kilometers. It is assumed by the theory that there is a reversal of the Earth’s magnetic field which is recorded by the oceanic crust.
The Earth’s mantle is solid in its state. This is because it has a solid structure which is characterized by the outermost layer, which is the earth’s crust. Different rocks and minerals are solidified into the mantle, and they have provided it a solid shape. Were the mantle in a liquid, gaseous or plasma form, it would not have held a proper shape. Moreover, the mantle has been formed from the liquefied lava, which has cooled over time and formed the solid mantle.