Sangiran -- Home to fossils of prehistoric man

By Nasruddin

SANGIRAN, Central Java (JP): Sangiran is just a hamlet on the island of Java, but its name has resounded throughout the scientific community since fossils of prehistoric man were discovered in the vicinity. For more than 100 years, scientists have tried to unveil the mystery of Sangiran's dark soil.

Thousands of pages have been written with competing theories that attempt to unravel the secrets of these prehistoric fragments. Conferences, seminars and publications about the findings have added luster to the name of Sangiran in world of archaeology, particularly in the field of paleoanthropology.

The geological layers of Sangiran form the most complete paleoanthropological site in Indonesia. Fossils of hominids have been found in a series of geological strata, which date from the late Pliocene period until the Middle Plestocene (between 2 million and 200,000 years ago). Hominids are two-legged, upright mammals, and include modern humans as well as the extinct ancestors of humans. The Sangiran fossils are those of the prehistoric Homo erectus, who evolved over a period of a million years. The Sangiran fossils make up 65 percent of all the hominid fossils found in Indonesia, and about 50 percent of the Homus erectus fossils in the world.

The different geological layers were formed by the shallow ocean (the Kalibeng layers), black clay (the Pucangan series), volcanic sediment (fasies fluviatil of the Kabuh series), and the muds of Notopuro which have sedimented above the Kabuh layers. Between the Pucangan and Kabuh strata there is often found a limestone layer, called grenz-bank.

The Sangiran site is located in a depression in Surakarta, also called Solo, at the foot of Mount Lawu. The site was once shaped like a dome, whose pinnacle was later eroded. The erosion created the depression, reversing the shape of site. The erosion has also uncovered the prehistoric ground layers in a natural way, revealing layers of human fossils and other vertebrates. These erosive processes are intensified by the action of the Brangkal, Cemoro, and Pujajar rivers -- offshoots of the Bengawan Solo which divides the Sangiran site in the north, center and south.

In administrative terms, the Sangiran site belongs to the Sragen district (Kalijambe, Gemolong and Plupuh regions), as well as the Karanganyar district (Gondangrejo region) in Central Java.

In 1934, splinters of tools made from jasper and calcedon stones were discovered by a Dutchman, G.H.R. von Koenigswald, above the Kabuh series in the west of the Kubah Sangiran sea. He believed that the gravel layer they were found in was formed at the end of the Middle Plestocene period, because these tools are associated with Trinil animals. Van Koenigswald's opinion was criticized by other researchers, including De Terra, Heekeren, and later Bartstra and Basoeki. They generally opposed the idea that the remaining vertebrates had resulted from primary sedimentation. They said the transformation of the sediment made it difficult to identify the age of the tools in relation to the gravel layers.

Two years later, another fossilized fragment of a hominid jawbone was found in the upper Pucangan series. After that, several skull fragments came to light in the Pucangan and Kabuh series. They were named Pithecantrophis robustus (Sangiran 4), Pithecantropis Dobius (Sangiran 5), Pithecantropis erectus (Sangiran 2 and 3), and Megantropus paleojavanicus (Sangiran 6a). The number of names reflects the diversity of the hominid fossils of Sangiran. Pithecantropus in itself has become a classical and historical term, and the species is usually described with by the alternative name, Homo Erectus.

Indonesian researchers, like T. Jacob and S. Sartono, took over paleoanthropological research in Java in 1960s. Research was also conducted by the Geological Development and Research Center in Bandung in cooperation with the Japan International Cooperation Agency. The Center focussed on prehistoric humans in Java, especially in Sangiran. Other cooperative works involving the National Archeological Research Center (PPAN) and the Museum National d'Histoire in Paris have been held since 1989 at the excavation site in Ngebung, leading to the discovery of human fossils in the Pucangan series. Massive tools and animal fossils were also found on the bottom Kabuh layer.

In the 1980s, Suzuki attempted to date the Sangiran findings using the fission-track method, while F. Semah and Yokohama tried the paleomagnetic technique. Because of these attempts at direct dating, the Sangiran site became increasingly well known.

Layers

The Sangiran dome in the Solo depression, is located at the foot of Mount Lawu, on the western seaside. The Sangiran site is considered the most complete in Java, because of its geological layering and the hominid fossils.

The Sangiran layers started with an oceanic layer (the Kalibeng formation), dating back to the Pliocene period, but only part of this layer has been exposed. The blue clay and ocean limestone of Upper Kalibeng is covered by volcanic laver.

Other layers, formed from black clay sediment before the Plestocene period, head towards the shoreline. Experts call this the Pucangan formation, which is 1.8 to 0.7 million years old. In this layer, scientists found the oldest fossil of Pithecantropus as well as the remains of huge mammals.

Fossils from several animal species were found in the Pucangan layers, along with several types of reptiles such as crocodiles and turtles. Closer to the surface of the earlier layers were cloven-footed herbivorous species such as deer and oxen. The layers also contain the fossils of pigs (Cercopithecidae) and monkeys (pongidae), and large animals like stegodon, hippos and rhinos.

Another level was discovered in Sangiran, between the borders of the Pucangan and Kabuh. Von Koenigswald introduced the expression, grenz-bank in 1940 to describe one-meter thick limestone strata which define the lower limits of the Kabuh layers.

According to Sartono, the grenz-bank indicates the borderline between the Kabuh series and the Pucangan layers below. The grenz-bank is a layer of super limestone made from various pisoid elements, like quartz minerals, fragments of frozen stones, clay, bone fossils, mollusks and large foraminifera shellfish.

The grenz-bank was formed through a slow process of erosion, through the action of the ebb and flow of the ocean tide. This layer was formed when erosion caused large quantities of "relief" material drift down the river, to eventually blend with other material in the Solo depression, creating the grenz-bank. This other material possibly originated from hills or from lagoons, and formed a course mixture.

After the Pucangan formation limited by the grenz-bank, is the Kabuh formation, which is about 500 to 600,000 years old. The Kabuh layer consists of river sand deposits mixed with volcanic material. Most human fossils of Sangiran were found in this section. Examples include Pithecantropus II and III, discovered by Von Koenigswald. Other scientists to locate Pithecantropus fossils were T. Jacob (S.10, S.38) and S. Sartono. Sartono discovered Pithecantropus VII and VIII, and the Sangiran fossil 17, the only one of its kind ever found.

Volcanic material from Notopuro was the last layer deposited in Sangiran before the dome folded inwards. It is difficult to date this layer, but it is estimated that huge volcanoes around Solo violently erupted between 300 and 100,000 years ago. The region was covered with volcanic material, containing large hunks of stone, lava and alluvial sand.

Scientists are still debating the nature of the cultural products of the prehistoric man known as Homo Erectus. There are few clear clues to indicate the cultural context in which these prehistoric humans lived.

Puech (1983) said that Homo Erectus from Java had no culture. Heekeren (1972) and Bellwood (1985) believed that the hominids made tools from materials, like wood and bamboo, which deteriorated over time. Semah (1992) has claimed that no cultural products have been found because of geological processes - the human fossils traveled long distances before finally settling in the alluvial deposits.

Recent research conducted on terraced deposits in Sangiran has divulged some of the cultural history of the Plestocene era. Ancient stone tools have been found in the lower layers of the Kabuh deposits. PPAN's 1992 excavations in Ngebung strengthened the interpretations about the presence of Homo erectus, with the discovery of a fragment of a jaw fragment, with two teeth attached, in river deposits dating back about 800,000 years.

The Nbebung site became important because of the discovery of stone tools, known as the Sangiran flake-industry. Chopper shards, cleavers, and faceted and un-faceted balls of andecit, made from splinters of calcedon and jasper, were discovered. Several researchers confirmed that the tools were cultural products of Homo Erectus in Sangiran. Fossils of vertebrate animals living in close proximity with prehistoric man suggest that suggest that people lived there 1.5 million years ago.

The richness of the Sangiran site had led experts to describe it as one of the human evolutionary centers of the world. It is further used as a measuring device to examine evolutionary processes in general.

The legacy of Java's Homo erectus from Java has no economic value, but it offers a priceless historical understanding of life in prehistoric times. The heritage does not glimmer with the glitz of gem stones; it consists only of fragments basalt and andesite rocks.

We may not realized that our present technology has arisen from a long process, which began with the stone tools of Homo erectus that have been found throughout Sangiran. These tools appear simple and they are barely recognizable among river stones, except to those who scrutinize the scene with archeological glasses.