Ferruginously-cemented gravels, sandy-gravels and sands, quarried originally from superficial, fluvial, fluvioglacial and glacial deposits, form an important building constituent of early London Basin churches. Their occurrence in the various churches relates very closely to the recognised geographical distribution of the respective, parent geological bodies. Similarly, clast compositions in the gravels of the different church fabrics reflect the understood geological sedimentary distribution patterns.The evidence suggests that London Basin churches which contain superficially deposited ferruginously-cemented materials in their walls are likely to possess Anglo-Saxon or earliest Norman origins.