100 K years? That's nothing.

Landfills, for one, will make for an interesting interval in the stratigraphic column. As they are fairly anoxic, they should cook nice and slow under a lithostatic load, but still be pretty immature after 100K. It might eventually reach a coal like nature, but the fossils within the bedding will be very interesting.

Say the sea level does rise, by several meters, and all us sapiens are outta the picture. Many major cities will be innudated. As the ocean trangresses over a city...let's say New York...the ruins of that city will be subject to several changing facies of both erosion and deposition. The worst is going to be a beach facies (environment) where everything gets pummeled by wave action. The iron will rust, the glass will remain, the concrete will be redeposited, and the plastic will begin to slowly degrade. After that, deeper water depositional systems will bury those ruins first in sand, then silt (+/- carbonate) then mud. Later, after a drop in sea level, new rivers will cut these deposits, exposing them to a future geologist's critical eye. There will be an apparent break in the fossil record of the species that have gone extinct. Many human remains will be fossilized and they will provide an important index fossil for the time period.

I could go on, and maybe I will, a bit later.