Physiography of Tripura The physiography of Tripura mainly consists of hills, valleys and plains which together form the physical landscape of the state. Nearly 60% of the total geographical area of Tripura is occupied by hills, while about 40% consists of valleys and plains. The state shows a typical folded relief structure formed by tertiary sedimentary rocks such as sandstone, shale and clay. These rocks were folded due to tectonic movements, resulting in a series of parallel hill ranges separated by valleys. The physiographic relief of Tripura is considered geologically young and immature. Erosion, weathering and river activities are still actively modifying the land surface. Continuous deposition of sediments in valleys and plains and erosion of hills are common processes shaping the landscape. The hill ran...