system
Given the following post, respond as if you're commenting on Reddit:
human
What will our landfills look like in millions of years?

I know that over time things like river beds turn into different colored layers of sedimentary rock based on what kind of silt was deposited so I was curious if something similar would happen to the trash we dump. As it gets covered over and is subjected to increasing pressure, what would plastics and other artificial products we throw away do to stone formation? Will we someday be able to dig up the equivalent to fossilized soda bottles?
gpt
If the conditions for cementation were met, you could get rock formation out of landfills, but it is unlikely it would resemble water deposited layers—these layers are formed because the river deposits material based on density and the energy level of the river.

 Landfill formed rock would be more like brecha: poorly sorted, with angular clasts. Metals would likely rust, forming bands in the rock, plastics may break down or may not depending on their composition. 

The preservation potential of soda bottles would depend on the substrate they were buried in—in many environments they would rust, but under the right conditions, you could see good preservation.  In general, the chance of preserved artifacts resembles the chance of preserved fossils: chemically stable materials in an unreactive substrate will last a long time, so it would depend on the landfill, and what was stored there, how deeply, and how much oxygen worked its way down there.