Rock layers, also known as strata, are distinct layers of rock that form over time through various geological processes. These layers can vary in thickness, composition, and color, often reflecting changes in the environment where they were deposited. For example, sedimentary rocks like sandstone and limestone are formed from particles and organic materials accumulating in water bodies. The study of rock layers is essential in understanding Earth's history, as they can reveal information about past climates, ecosystems, and geological events. Fossils found within these layers provide clues about the types of organisms that existed at different times, helping scientists reconstruct the evolution of life on Earth.