Here's why:

* Sedimentary rocks are formed from the accumulation and cementation of sediments, such as sand, silt, clay, or even the remains of organisms.

* Layering (stratification) is a characteristic feature of sedimentary rocks because the sediments often settle in distinct layers.

* Erosion is the process of wearing away rock by natural forces like wind, water, or ice. As erosion occurs, it often removes the top layers of a sedimentary rock, revealing the layers underneath.

Examples of sedimentary rocks that show layering:

* Sandstone: Formed from cemented sand grains, often showing distinct layers of different colors or grain sizes.

* Limestone: Formed from the accumulation of marine organisms, which can show banding patterns or distinct layers of fossils.

* Shale: Formed from compacted mud and clay, often showing very thin layers.