Why is sedimentary rock more common on Earths surface than metamorphic or igneous rock?
Erosion and weathering of igneous, metamorphic, and sedimentary rocks eventually leads to formation of more sedimentary rock. Additionally, huge areas of continents have been covered by inland seas at one time or another in geologic time creating vast amounts of sedimentary rock. Plate tectonics also plays a role in the thrusting upward of areas that once were ocean floor.
