Uluṟu and Kata Tjuṯa are made of different types of sedimentary rock. Uluṟu is mostly made of arkose, a hard type of sandstone that contains a lot of the mineral feldspar. The sediment originally comes mostly from granite. Kata Tjuṯa is made of conglomerate, which consists of bits of rock that has been cemented together by sand and mud. The sediment in this rock is a mixture of granite, gneiss and basic rocks.