ABCTE Science Practice Exam

Sandstone is classified as a sedimentary rock because it forms from the accumulation and lithification of sand-sized particles. These particles are typically derived from the weathering and erosion of pre-existing rocks, which are then transported by wind or water before being deposited in layers. Over time, pressure and mineral cementation solidify the layers into sandstone.

The characteristics of sedimentary rocks, such as their layered appearance and the presence of fossils, are key indicators that differentiate them from igneous and metamorphic rocks. While gabbro is an igneous rock formed from the cooling and solidification of magma, schist is a metamorphic rock that results from the alteration of other rocks under high pressure and temperature. Marble, similarly, is a metamorphic rock formed from the recrystallization of limestone. These distinctions underscore why sandstone is the correct choice as a sedimentary rock.