Allowing 4 erosion and redepostion, how deep do you have to dig in your backyard before hitting ancient dirt?

Question

If you wanted to look for fossils in your own backyard, or just ancient artifacts, etc. how deep would you have to remove the top layers of topsoil and clays or sandy dirt before reaching a stable zone that is immune to erosion? And how do you date it, for your specific geographic area? Are there specific depths or signs to look for when reaching a certain depth? Specifically in northern Virginia, USA near Occoquan river.

Answer 1

Generally you wont find fossils in soil. You may find some old buried junk though. The chances of finding fossils in your backyard are pretty slim unless you are in the right area. You may have more of a chance of finding fossils in mud/silt/slate stones and limestones. But they must be the right age. Fossils can occur at any depth from the surface so digging down wont necessarily produce a specimen

Answer 2

Depending on how you wanted to define ancient - a few feet. In my back yard you go down about 3.5 feet and hit white rock (gypsum). If you look at flat excavations shown in videos, like Jamestown, they are going down only a few feet.
Old bones may be found at any depth, as with the guy who found an old bison head with a spear point in it in a river bank in Oklahoma, depending on the luck of the previous erosions.
Fossils are going to be found in rock, so you are talking about roadside cuts, etc., not digging in your backyard.