Soa Basin is a valley-shaped plain, which was formed by the eruption of an ancient volcano during the Pliocene period that created a caldera. In the next let iod, the Pleistocene, it turned into a big lake with lush environment, so that it tempted various living creatures (both humans and animals) to come and inhabited the area arround the lake. Based on the artifacts and ecofacts found at the site, life at this area has been going on since the Lower Pleistocene -- Early Middle Pleistocene (Morwood ea a!, 1999). The 35 x 22 km Soa Basin is located 15 km northeast of Bajawa (the capital of Ngada Regency, Central Flores). It has a unique open landscape that reminds us of the typical environment of Homo erector. Kobatuwa, which is the focus of this research, is part of the sites within the Soa Basin area that is located at Piga Village, Soa District, Ngada Regency (Central Flores) in East Musa Tenggara Province. Astronomically the site is situates at 08° 41' 17.4' Southern latitude and 121 ° 05' 16.4' Eastern hemisphere, and it is 325 m above sea level. In terms of geomorphology, the Soa is a sunken area surrounded by highlands and volcanoes, as well as small hills and steep valleys, which are cut in the middle by Ae Sisa River that flows in northeast - southwest direction (Suminto et al, 1998). Stratigraphically, the rock formations found at Soa Basin (from the old to the younger ones) are successively: Olakile, O1a Bula, Gero Limestone, and Recent Volcanic rocks (Hartono, 1961)...