Universal Journal of Geoscience 6(2): 47-54, 2018 http://www.hrpub.org DOI: 10.13189/ujg.2018.060203 On the Geomorphology and Tectonic Position of Ciletuh-Jampang Area, West Java, Indonesia Iyan Haryanto, Adjat Sudradjat * Faculty of Engineering Geology, Padjadjaran University, Bandung, Indonesia Copyright©2018 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract The Ciletuh-Jampang area is located in the western tip of the Southern Mountain of West Java, Indonesia. The area is presently well publicized in an effort to bring the unique geological characteristics exposed in this particular place to become the Global Geopark Network (GGN) of UNESCO. Ciletuh area exhibits a rare mega-aphitheater morphology. Stratigraphically West Java composed of clastic sediments of continental and volcanic island arc origin with the interruption of sub-aerial volcanic rocks and the coastal reefs banks developed along the coasts both in the north and the south. The age of the rock ranges between Eocene to Recent. The analysis of regional structure shows that a set of deep seated faults was recognized dominating the area in NNW-SSE and NNE-SSW directions. The released faulting occurred in E-W direction. The low angle shallow upthrustings facing north of skin structure in E-W direction dominate the upper part of the rock sequence. The structural analysis revealed the continuous prevailing stress field in SSW-NNE direction since Eocene time. The advancing landslides are readily observable in the rim of the amphitheater of Ciletuh. This phenomenon seems to demonstrate the initial stage (primarumpf) of the geomorphologic cycle taking into account the flat surface of Jampang area in the surroundings. Further investigations revealed the geomorphologic evidences of the formation of plateau, namely the erosion surface, old terraces, mountain tables, old beach ridges and the characteristics of drainage pattern. Two remnants of main plateau were recognized in Ciletuh-Jampang area, namely Bentang Plateau and Jampang Plateau. Further investigations show that at least five locations of plateau were identified in western part of Java Island, namely Dieng Plateau (+ 2,000 m), Pengalengan Plateau (+1,300 m), Bentang Plateau (+ 1,000 m), Jongrangan Plateau (+ 850 m) and Jampang Plateau (+ 700 m). A rough estimation reveals the annual rate of lifting in Java Island since Pliocene time ranges most likely between 5.0 and 5.4cm. Keywords Amphitheater, Initial Stage, Plateau, Uplifting, Skin Tectonics 1. Introduction Ciletuh-Jampang area is located in southern part of West Java. Geographically it extends from the longitudes of 106 0 20’ to 107 0 00’ East and the latitudes of 07 0 00’ to 07 0 45’ South (Figure 1). To the west the area is bounded by Banten Province, to the South by the open sea of Indian Ocean, whilst to the North and East it has common boundaries with Bogor and Cianjur Residencies respectively. The area is located about the same distances from Jakarta, the capital city and from Bandung the Province city, namely 125 kilometers away. The investigated area is covered mainly by rubber and tea plantations. Recently the coconut palm replaces the old rubber plants. Due to the difficult access the area remains relatively virgin. The rare turtle of the Indian Ocean used to lay their eggs in the white sandy beaches in the investigated area. Fishermen live in the embayment of the coastal area. The arable land is limited to the valleys in the vicinity of the coast. The off-road vehicle is the mode of transportation from Pelabuhan Ratu a local fisherman’s harbor located about 25 kilometers NNE of the investigated area. The other access is by fishing boat directly from Pelabuhan Ratu. In the rough sea at the western monsoon however, the sea transportation might be inconvenient. The terrain mostly consists of rugged topography, geologically known as Southern Mountains. At the crest of the mountain, a rather flat topography however exists. The Southern Mountain composes of Miocene volcanics with the interruptions of clastics sediments deposited in the shallow marine environment. An escarpment of Cimandiri fault bounds the topography from the relatively smooth Quaternary volcanic terrain in the North. Ciletuh-Jampang area is intensively investigated to obtain the recognition as the candidate of the Global