Terrace sediment had been deposited along Cemoro River, Brangkal, and Pohjajar in the form of Conglomerate deposit, gravel-coarse structure, intermitted by thin layers of clay. The oldest terrace sediment spread at around Triangulation in Ngebung Village, whenever the younger can be found in the slope of hills in Sangiran. Those rivers’ terrace sediment, was kept fauna fossil and early man culture in the form of stone tools. But the contexts of those findings are difficult to be identified, whether
from a far of river’s coarse, or the eroded layer from those terrace sediment.
The youngest sequence of Sangiran was filled with alluvial sediment in the form of clastic sediment, deposited on flood plate. The river tried to maintain its flow when Sangiran was lifted and formed a dome. Sometimes, turning, following the track which is easily eroded. The area of river, which was left and was not swept by maximum flood, is known as river’s terrace. The sediment is called terrace sediment. (Suwita Nugraha, Wulandari, Iwan SB)