How has archeology a thing? Why is so much of our history found under the ground we reside today? Why do we have to dig down to find ancient towns? What happened?
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The way erosion and deposition works is that material is taken from one place and dropped in another place. We do not find stuff in the place where it is taken away and moved to somewhere else (it is gone). When material erodes, it is lost.
On the other hand, though, that dirt ends up somewhere, generally in valleys and on the plains (wind and water are dumping dust, silt, sand everywhere, all the time, even if it is fairly slow in our terms). Thus, if there is going to be something left to find, it is because it got buried rather than eroded away. We only find what got buried, and thus protected against erosion. The stuff that wasn’t buried? Can’t find it because it is gone, broken up into tiny bits and scattered across the face of the earth.
Sometimes, structures made by man are exposed to wind and water and ought to be eroded away, but the walls and other features create traps for sediment, and mounds develop where humans once lived, so not everything we find was once in a low area at the start. Sometimes, our constructions are sediment traps and sediment settles down where it normally would not have done if not for the walls or whatever.
Think about how buildings sometimes act to make snowdrifts in winter (can even bury a building), but sometimes the buildings actually make it so the snow is scoured away and the building is surrounded by no snow at all (all the snow got blown away next to the building). Dirt does the same thing but is a lot slower to accumulate or erode.
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