Soon after the volcanic sediment of Notopuro Formation was sediment, endogen power from earth, with exogenous power from the mass of Sangiran land, causing the layer in the middle of Sangiran area, to be a dome.
The layer in the peak of the dome, are mostly having the cracks. The erosion was slowly started and produced the curve. The result of erosion has displayed the record of early man evolution along with their culture and environment, which stitch into every layer of Sangiran. (Suwita Nugraha, Wulandari, Iwan SB)