Gunung Sewu is an enormous mountainous limestone zone, marked by conic karst hills spanning Yogyakarta, central and east Java. The karst landforms grew through dissolution, when the limestone was uplifted from the seabed about 1.8 million years ago. The uplift notably led to the formation of coastal and river terraces as well as sandstone outcrops. The earliest signs of human presence date back 180,000 years, with evidence of settlements along the riverbanks and in limestone rock-shelters and caves. The stone-terraces that surround almost every hill bear witness to local-knowledge passed from generation to generation to preserve a relatively thin soil for agriculture.