Here's a breakdown:
* Igneous rocks: Form from the cooling and solidification of magma or lava. They represent the vast majority of the Earth's crust.
* Sedimentary rocks: Formed from the accumulation and cementation of sediments, which are derived from the weathering and erosion of pre-existing rocks (igneous, metamorphic, or other sedimentary rocks).
While sedimentary rocks cover a large portion of the Earth's surface, they form a relatively thin layer compared to the thick, underlying igneous rocks.
Here's why:
* Formation: Igneous rocks are formed directly from molten rock, making them the primary building blocks of the crust. Sedimentary rocks are derived from the breakdown of these primary rocks.
* Cycle: The rock cycle constantly recycles rocks. Igneous rocks are melted and reformed into new igneous rocks, while sedimentary rocks can be eroded and re-formed into new sedimentary rocks, or even melted and transformed into igneous rocks.
* Thickness: Igneous rocks form the vast majority of the continental and oceanic crust, creating a thick foundation. Sedimentary rocks accumulate on top of these igneous rocks, forming a much thinner layer.
Overall:
The majority of the Earth's crust is composed of igneous rocks. Sedimentary rocks, while important for understanding Earth's history and providing resources, make up a much smaller proportion of the overall crustal volume.
