[Taipei]

In anaerobic conditions, such as very wet or waterlogged soils, the lack of oxygen drastically slows the processes of decomposition.

[Snickering Hound]

In anaerobic conditions, such as very wet or waterlogged soils, the lack of oxygen drastically slows the processes of decomposition.

It's how you get petrified wood. Just takes much more time.

[ProtectOurFreedom]

Understand about anaerobic conditions, but 171,000 years? Also, look at the soil in the photo. That doesn’t look like a peat bog but regular soil.