The World Heritage Site of Sangiran in Indonesia has major importance for the understanding of human dispersals and settlement in eastern Asia in the Early Pleistocene. The Sangiran site is one of the most productive sites in human paleoanthropology, and it has produced a steady stream of Homo erectus fossils, now totaling over 100 specimens. However, it has long been lacking an accepted chronology ; the timing of the first appearance of Homo erectus in the region has been especially controversial.

This paper outlines the history of studies on the chronostratigraphy of the Sangiran site, noting that it has been widely accepted for the past two decades that Homo erectus reached Sangiran more than 1.5 million years ago, although other studies have failed to support this chronology. The paper also summarizes our recent research findings which make a seminal contribution to the chronological framework of the Sangiran site and should represent crucial steps to the resolution of the controversy. The first appearance datum for the Sangiran hominin fossils is now resolved to be best considered ca. 1.3 million years ago and less than 1.5 million years ago, which is significantly later than the dates widely accepted over the last two decades.

The topography of the Atosanupuri volcanic complex was analyzed using 1mDEM and 1 : 10,000 lake maps. The geomorphic development of the Atosanupuri volcanic complex was investigated by studying the detailed distribution of the lacustrine landform surfaces on the shore of Lake Kussharo and below the lake surface, and the volcanic fault group of the Atosanupuri volcanic complex. The elevation of the lake surface of Lake Kussharo was more than ca. 40 m above the present lake surface until after ca. 15 cal ka, and then decreased intermittently by ca. 60 m over ca. 7.6 cal ka. After that, it rose to the present lake level due to channel blockages caused by the Mashu-f pyroclastic flow and the Rishiri debris avalanche. After ca. 15 cal ka, the dome-shaped uplift of the Atosanupuri volcanic complex became active, displacing the lacustrine terraces on the eastern shore of Lake Kussharo by up to 50 m, with an average uplift rate of ca. 3.7～6.5 m/kyr. At the same time, a volcanic fault group was formed in the region of the dome-shaped uplift, and a 1 km-wide graben with an axial orientation of NE-SW or E-W strike was formed in the center of the group. The lowest lacustrine terrace surface is found only in a part of the eastern shore of Lake Kussharo, suggesting that the dome-shaped uplift has continued in recent years.