The upper part of the mantle above the Earth's crust and the asthenosphere of the mantle is composed of minerals and rocks, collectively referred to as the 'lithosphere.'

The thickness of the lithosphere is uneven, with an average thickness of about 100 kilometers. The lithosphere is closely related to modern geophysics and geodynamics and is the part of the solid Earth that has been studied the most and in the most detail in modern Earth science.  

Lithospheric plate tectonics

Plate Tectonics Theory

The theory of plate tectonics was proposed on the basis of the continental drift theory and the seafloor spreading theory. Plate tectonics holds that the lithosphere is not a rigid whole, but is divided by various faults and structural activity zones into blocks that 'float' on the asthenosphere. These blocks are called plates. The lithosphere is composed of six major plates, each of which is further divided into several plates of varying sizes.

Transformation of the Three Major Rock Types

The three major types of rocks have different formation environments and conditions, and these environments and conditions change with the occurrence of crustal geological processes. In geological history, some rocks are always being formed while others are disappearing. The three major types of rocks constantly transform into each other, and our Earth is like a giant rock factory.

(1) Metamorphic Rocks

Due to the high heat and high pressure deep within the Earth, these rocks undergo an entire transformation process from their original form. Unlike igneous rocks, metamorphic rocks never truly melt; all their changes occur in the solid state. In some cases, the transformation pressure comes from the original rock being continually buried; more often, the transformation pressure comes from the intense forces generated by crustal movements. Under these conditions, solid rocks can actually flow like toothpaste, which often leads to the twisting and bending of rocks accompanied by a set of new minerals replacing old minerals.

(2) Sedimentary Rocks

After granite bodies are exposed to the surface through large-scale tectonic movements, they begin to undergo weathering and erosion under natural geographic conditions. If tectonic movements create the general outline of granite landforms, then temperature changes, wind erosion, precipitation, and biological weathering further shape and 'refine' the landforms, ultimately forming the diverse granite landscape we see today.

(3) Igneous Rocks

Igneous rocks refer to those rocks that originate from a high-temperature molten liquid called magma. The term 'igneous' comes from Greek, meaning 'born of fire.' Magma from deep underground flows slowly on the surface, and if it flows everywhere, the liquid rock called lava will erupt. Lava accumulates layer upon layer, forming a ridge known as a volcano. Volcanic rocks cool quickly enough that there is no time for large mineral crystals to form.