The bedrock geology of the parish comprises rocks formed in the Santonian and Campanian ages of the Cretaceous period and the Eocene age of the Palaeogene period. In places these are overlain by younger Quaternary drift material: river terrace and head deposits, clay-with-flints, and alluvium—the last found only in the valley floors of the larger watercourses. On Puddletown Heath (now mostly covered by Puddletown Forest) are more than 370 solution hollows or sinkholes; these constitute the largest concentration of hollows on the heathlands in the area.