Palaeoenvironment and Palaeoecology of the Lower and Middle Siwalik Subgroups of a Part of Northwestern Himalaya

The faunal assemblages from the red bed successions exposed at Ramnagar (J.&K.) and Nurpur (H. P.) have been used to reconstruct the palaeoenvironment and palaeoecology of the two areas. The two assemblages are of different ages. The succession at Ramnagar is equivalent to the Chinji Formation (Astarcian) of the Lower Siwalik Subgroup, whereas the Nurpur succession represents the Middle Siwalik Subgroup (Turolian). Red mudstones are dominant in both areas and indicate deposition in a meandering fluvial regime with broad flood plains, but in Nurpur, occasional high energy conditions also existed, as suggested by the presence of multistoried sandstone bodies.

The faunal assemblages of the Ramnagar and Nurpur areas comprise aquatic and semi-aquatic, arboreal and terrestrial communities. The terrestrial community, represented by mammals, is the most dominant in both areas. In the Ramnagar assemblage, suids, tragulids, bovids and giraffids are better represented and point towards a tropical humid environment with prominent swampy conditions. In Nurpur assemblage, besides suids, tragulids and bovids, hipparionines and large giraffids are common. This suggests reduction of tropical rain forests and development of wide and open grasslands separated by tree canopy forests. The habitat characteristics of the various taxa have been discussed to work out the palaeoecology of the two areas.