Both counties are near the fall line and have highly erratic soil types. I lived and worked (forestry) in Macon County and know that it goes from deep sands to montmorillinitic clays (slick grey "gumbo" clay) to more typical red clay found in the Piedmont. There is no typical soil type in the area immediately south of the fall line. Look at a statewide soil map and you'll see what I mean.