What type of rock is primarily composed of sedimentary materials and can be found over 20,000 feet deep in some places?

Sedimentary rock is primarily formed from the accumulation and compaction of mineral and organic particles, such as sand, silt, clay, and the remains of living organisms. These rocks often develop in layers over time as sediments are deposited in environments like rivers, lakes, and oceans. One key characteristic of sedimentary rocks is that they can be found at significant depths, such as over 20,000 feet in areas like ocean basins or sedimentary basins where they have built up over millions of years. These rocks can also preserve fossils, providing valuable geological and biological insights.

In contrast, the other types of rocks mentioned do not primarily compose sedimentary materials. Igneous rocks form from the cooling and crystallization of molten material, while metamorphic rocks arise from the transformation of existing rocks under heat and pressure. Granite, specifically, is a type of igneous rock composed mainly of quartz, feldspar, and mica, and is not classified as sedimentary. Therefore, sedimentary rock is correctly identified as the type of rock that meets the criteria presented in the question.