The speed of deposition is super variable. In fluvial environments, I've seen reports of feet per year, which put recent sites (i.e. medieval) under 40+m of sed

The speed of deposition is super variable. In fluvial environments, I've seen reports of feet per year, which put recent sites (i.e. medieval) under 40+m of sediment. On the other hand, I've worked sites with long term 'stable surfaces', where layers thousands of years old were within centimeters or less of modern contexts.