Good call, babble-on! Also,it depends on the site. Erosion, windborne debris, earthworm activity, the crumbling of the ancient structures, reuse by building over the older habitations, and (my personal favorite) using the abandoned town site (or parts thereof) as a refuse pile all can contribute to the burial.
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Cantil, California
Was once thriving, even farming. Till the water got sucked out.
Now the uninhabited buildings are half deep in blown sand.
A few souls still inhabit the area, but have to fight the sand invasion.
Town founded about 1908. Give it a little more time to get all buried.
One of the Renaissance-era sculptors decided to dig a basment under his house. A few feet below the floor he ran into a flat stone slab.
It turned out to be the top of a capital, the kind used at the tops of columns.
In trying to dig it out, he found the column was still there.
The rest of the ruined, buried building was also still there.