Forest Marble

Forest Marble, a member of the middle division of the Jurassic System (q.v.), so called because of the occurrence of the typical beds in Wychwood Forest, Oxfordshire. The principal bed is a fissile limestone, containing large numbers of dark-coloured shells (chiefly Ostrea and Pecten), and capable of sustaining a fine polish. On this account it is used to some extent as 'marble.' It is interstratified with beds of clay and shale, occasional marls, and sandstones. The thickness of the group in North Dorsetshire is 450 feet, but it thins away northwards, being about 100 feet near Bath and Cirencester.