Please watch following Scratch project where you can see simulation of weathering and erosion in nature through water movement.

https://scratch.mit.edu/projects/380743881/

Steps :

1. For stage, select backdrop of Water and Rocks.
2. Draw 1 sprite of big,brown rock and select another rock sprite from the library. Change color of blue rocks to black rocks.
3. For brown rock sprite, we will add blocks to make the rock look like rolling and becoming smaller during seasonal changes. So it needs to add blocks that change backdrops to bring season changes and blocks to make the boulder rotate and glide as well as decrease it’s size.