The convection cell in the mantle is essentially the self-sustaining, constant movement of the magma inside this layer. This works in a very simple way. The hotter magma is less dense, so it is pushed upward toward the crust above it, while the cooler magma is denser, and it moves downward where it gets hotter, and the process goes on and one. The magma that goes upward toward the crust, manages to push through the thinner and cracked crust between the plates that move away from each other, thus on the divergent plate boundaries. As the magma penetrates through the crust it manages to get to the ocean floor, thus causing volcanic activity. This magma cools of very quickly and creates new crust. Because the magma constantly rises up and creates new crust, the crust piles up and forms an underwater mountain of volcanic origin that constantly has volcanic activity because of the rising magma. This volcanic underwater mountain range is called mid-ocean ridge.
Soil is medium for plant growth and is an earth supporting layer called as pedosphere. <u>Some physical and chemical properties of the soil are its mineral content, texture, exchange capacity, density, porosity, color, depth, fertility, and pH values.
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As soils hold about 50% solids i.e 45% mineral and 5% organic matter given sufficient time the soil profiles emerge and these consist more than 5 layers. <u>Like A, B, C, D, E and H horizons</u>.
Soil texture includes article size such as sand, silt and clay and their interaction with organic matter such as water and gaseous biotic components give its terms of color, porosity and pH content to the soil. Its a commonly known fact that humus-rich soils are found at the top horizons and bedrocks at the bottom E horizons.
Plant's roots go deep into the soils and hold these soils and don't let them wash away and thus enhancing the nutrient content in the soil again. Thus the organic content of the soil is balanced by a new matter that falls from above.