From the marine environment under the Tethys Sea, the land was raised slowly and exposed to the warm climate of the tertiary period. It appears that the land escaped the Pleistocene glaciation of the early Quaternary. But, it remained cool and dry. There is no geological evidence of Quaternary glacial or periglacial climate upto an elevation of about 1500 m a.s.l. In fact, ferruginous (oxidised) cement and matrix of gravel formations in the region suggest a sub-tropical Quarternary (Joshi et al., 1979). The climate in the late Quaternary was warm and humid (Thokchom, 1984) and it has not changed drastically since then.