system
Given the following post, respond as if you're commenting on Reddit:
human
So Earth has layers and layers of dirt and rock that we are able to check and see from different periods in the history of Earth. How? Like how does layers of Earth keep getting added, wouldn’t it stay the same? Clearly not but why not?
gpt
Rock gets eroded by wind and water into smaller rocks and sand and gravel. This tends to settle wherever it is to the bottom. These layers are called strata, by the way. 

For example, fill a jar with rocks and sand and water and shake it up. You'll find the particles will settle smallest to biggest. 

Then, over time, this gets compacted into rocks. Rinse and repeat. Erosion is a constant process -- it can be very slow (eg, a light breeze) or very fast (a river running).

It's a very long process. It can easily take hundreds of thousands to millions of years, and this doesn't even consider other things like igneous and metamorphic rocks.