What is the main feature of sedimentary rocks?

The main feature of sedimentary rocks is that they are typically layered and can contain fossils. This layering occurs due to the accumulation of sediments over time, which can include fragments of other rocks, minerals, and organic materials. As these sediments settle in various environments—such as riverbeds, lakes, and oceans—they gradually compact and cement together, forming distinct layers that often reflect changes in the environment or sediment supply.

Fossils found within sedimentary rocks provide vital information about past life and ecosystems, as sediments can encase organic materials, preserving them for millions of years. This characteristic of containing fossils is especially important for understanding geological history and the evolution of life on Earth.

Other options focus on different types of rocks or geological processes. For example, volcanic activity primarily leads to the formation of igneous rocks, while immense pressure is more commonly associated with metamorphic rocks. Similarly, crystallized minerals typically refer to the process involved in forming igneous or metamorphic rocks rather than sedimentary. Thus, the presence of layering and fossils distinctly identifies sedimentary rocks from other rock types.