Of the four major geographical areas where fossil hominids are found, Southeast Asia is the least understood. Except for some isolated teeth, the only fossil hominid remains in Southeast Asia are from sites near the Ngandong (Solo) River of central Java, Indonesia. Of fossils sites in central Java, Sangiran is the most important. The villages in Sangiran are famous among paleoanthropologists because they lie on sedimentary layers rich in the remains of Homo erectus and other extinct plants and animals. Fossils from the dated volcanic levels of Sangiran indicate that Homo erectus lived in the Sangiran area for almost two million years.
Approximately 150,000 years ago, volcanic pressure pushed the Sangiran area into a volcanic dome. This dome has been eroded by natural forces (rivers, rain, and humidity) into the depression that exists today. Currently, the Javan Plio-Pleistocene is subdivided into four major geological formations: the Kalibeng (Upper Pliocene), the Pucangan (Lower Pleistocene), the Kabuh (Middle Pleistocene), and the Notopuro (Upper Pleistocene). The Sangiran Dome deposits exceed 300 meters in thickness and encompass all four formations. With the exception of the Kalibeng, these deposits have yielded at least 100 fossils and numerous teeth of Homo erectus and Homo meganthropus.
The importance of the site of Sangiran was determined by paleoanthropologist Ralph von Koenigswald in the 1930s. The site of Sangiran is filled with cereal grains grown by the local inhabitants. In the process of farming and seasonal monsoon rains, the deposits of Sangiran continue to be eroded, yielding the remains of Homo erectus and dozens of other mammals such as buffalo, turtle, crocodile, hippopotamus, rhinoceros, and elephants. These farmers have an intimate knowledge of where fossils can be found. Von Koenigswald quickly recognized the farmers’ knowledge and offered payment for fossil humans.
At first, Von Koenigswald was paying the farmers for each fragment that they brought to him. He changed his policy when he discovered that the farmers were breaking large fragments into several pieces to get more money. In the early 1960s, an Indonesian geologist/paleoanthropologist, S. Sartono, continued the work of Von Koenigswald and taught the local people how to identify human fossils. Nearly all of the important specimens from Sangiran have been found by local farmers who removed them from their original locations and brought them to Sartono. Because they were not found in a controlled archaeological excavation, the dates of the important specimens remain problematic. In 1996, the importance of the Sangiran site was recognized and protected as a World Heritage Location by UNESCO.
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