Here's why:
* Lithification is the process by which sediments are transformed into solid rock. This involves compaction (squeezing out water and air) and cementation (minerals crystallize between sediment grains).
* Weathering is the breakdown of rocks, soil, and minerals through direct contact with the Earth's atmosphere, water, and biological organisms.
* Erosion is the movement of weathered material from one location to another by wind, water, ice, or gravity.
Weathering and erosion break down existing rocks, essentially reversing the process of lithification. They create loose sediment that can then be transported and potentially lithified again in the future.