Source: Marjorie Cropp, Salute to Oxford, page 55, Beachville District Museum Reference Library
The flats around the Thames River were the perfect place to mine limestone. In this image, notice how shallow the soil is atop a major sheet of rock. Accessing the stone meant stripping the land of brush, layers of soil, and sand that lay on top. These obstructions to the stone were referred to as the “overburden.” After the overburden was hauled away, the top of the rock was swept clean with brooms, and extraction would begin. Quarrying was done at the river flats because stone supplies could be found only 3 or 4 feet deep.