_:b1216776 . _:b1216776 "A closed depression draining underground in karst, of simple but variable form, e.g. cylindrical, conical, bowl- or dish-shaped. From a few to many hundreds of metres in dimensions."^^ . _:b1216776 . _:b1216776 "web:http://wasg.iinet.net.au/terminol.html"^^ . _:b1216776 .