Very rarely can you find such vertical formations, even in mountains. However, even mildly sloping formations or domes or basins may expose formations from different time periods. Gravity Gravity pulls water and sediments downhill. Thus, erosion is generally greater at higher elevations. Imagine dumping a bucket of sand on a mountain peak.
Sediments tend to collect at low elevations and in depressions in the earth.
For example, lakes and dams are constantly filling with silt. Once a depression that cradles a lake has been filled to the brim with sediment, it s no longer a lake. Sediments that are carried away by rivers may come to rest on riverbanks, or they may be carried into larger rivers that empty into the sea. Also, note that rivers flow faster on steeper terrain. In contrast, streams fed by glaciers high in the mountains may crash down in waterfalls and rapids.