The most common rock type found in the Earth's crust is igneous rock.

While it's true that sedimentary rock covers about 75% of the Earth's surface, most of that is relatively thin layers on top of the igneous bedrock.

Here's why igneous rock is the most abundant in the crust:

* Formation: Igneous rocks form from the cooling and solidification of magma (molten rock) or lava. This is a fundamental process in the Earth's crust.

* Underlying Bedrock: Sedimentary rocks are formed from the weathering and erosion of existing rocks, including igneous rocks.

* Volcanic Activity: Volcanic activity constantly adds new igneous rocks to the crust.

Important Note: While igneous rock is the most abundant, the relative amounts of different rock types can vary greatly depending on the location.