what is the primary composition of the solid, rigid lithospere?
The primary composition of the solid, rigid lithosphere is mainly composed of two major components: the crust and the uppermost part of the mantle.
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Crust: The crust is the outermost layer of the Earth’s surface, which includes both continental and oceanic crust. The continental crust is relatively thicker and less dense compared to the oceanic crust. It is primarily composed of granitic rocks, such as granite, and sedimentary rocks. On the other hand, the oceanic crust is thinner and denser, mainly composed of basaltic rocks.
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Upper Mantle: The uppermost part of the mantle lies beneath the crust and extends to a depth of about 100-150 kilometers. It is composed of solid rock material made up of silicate minerals, such as olivine and pyroxene. The upper mantle is relatively more rigid compared to the underlying asthenosphere, which is partially molten and has a plastic-like consistency.
The lithosphere is divided into several tectonic plates, which are sections of the Earth’s crust and uppermost mantle that move and interact with each other. This movement of tectonic plates is responsible for various geological phenomena, such as earthquakes, volcanic activity, and the formation of mountain ranges.