A dolmen, also known as a cromlech, portal tomb, portal grave or quoit, is a type of single-chamber megalithic tomb, usually consisting of two or more megaliths supporting a large flat horizontal capstone ("table"), although there are also more complex variants. Most date from the early Neolithic (4000-3000 BCE). Dolmens were typically covered with earth or smaller stones to form a tumulus. In many instances, that covering has weathered away, leaving only the stone "skeleton" of the burial mound intact.