the western "lower karoo" (the tankwa karoo and moordenaarskaroo) contain remnants of the cape fold mountains (e.g. the witteberg and anysberg mountains) which give it a moderate hilly appearance, but further east, the lower karoo becomes a monotonously flat plain. the "upper karoo" has been intruded by dolerite sills (see below), creating multiple flat-topped hills, or karoo koppies, which are iconic of the great karoo.