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In The Forty Sixth Annual Convention and Meeting on Evo- lution of Himalayan Foreland Basin and Emerging Challenges, Wadia Institute of Himalayan Geology, Dehradun, Abstract, 2009, pp. 44–45. ACKNOWLEDGEMENTS. We are grateful to Prof. A. N. Sial, NEG- LABISE Department of Geology, Federal University of Pernambacu, Recife, Brazil, for isotopic analysis of the Lakadong Limestone from Meghalaya. V.C.T.’s discussions on Tethyan Paleogene foraminifera and calcareous algae with Prof. Katica Drobne (Slovenia) and Prof. N. Pugliese, Drs Romana Melis and Roberta Romano, DisGam, University of Trieste, Italy, have been very fruitful. We thank Prof. B. R. Arora, Director, Wadia Institute of Himalayan Geology, Dehradun for facili- ties and permission to publish the paper. We also thank the authorities of the Mawmluch-Cherra Cement Ltd for the permission to sample in the Limestone Quarry. Received 19 March 2009; revised accepted 23 November 2009 Stream profiles as indicator of active tectonic deformation along the Intra-Foreland Thrust, Nahan Salient, NW India Tejpal Singh 1,2, * and A. K. Awasthi 1 1 Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247 667, India 2 Present address: CSIR Centre for Mathematical Modelling and Computer Simulation, NAL Belur Campus, Bangalore 560 017, India Stream profiles along five major streams from the Nahan Salient in the Western Sub-Himalaya were investigated with special emphasis on reactivation/ active tectonics of the Intra-Foreland Thrust (IFT). Each of the stream profiles is observed to consist of two to three segments of different stream gradients. Each segment comprises a ‘stream reach’ and is marked by a distinct stream-length (SL) gradient index. SL index curves drawn for the five streams show anoma- lous increase in its values at the contact of two stream reaches. These distinct anomalies are found associated with the surface exposure of IFT in the field. Likewise low mountain front sinuosity (1.1 to 2.4) and low valley width to height ratios (0.1 to 0.33) also reflect active tectonic deformation along the IFT due to reac- tivation. The present stream profile approach is sim- pler, easier and faster to locate sites of fault related reactivation. Keywords: Intra-Foreland Thrust, Nahan Salient, reac- tivation, stream long profiles, SL value. THE Sub-Himalayan belt in the NW India is marked by the sinuous trace of the Main Boundary Thrust (MBT) giving rise to areas that are concave towards the foreland, known as reentrants, and areas that are convex towards the foreland, known as salients. The present study was carried out in the largest salient of NW India, i.e. the Nahan Salient (Figure 1). The Nahan Salient is located in between the Kangra and the Dehradun reentrants lying in its northwest and southeast respectively. The salient and the reentrants are marked by thrusts running parallel to sub-parallel to the Himalayan Frontal Thrust (HFT) in the NW–SE direction. It is commonly believed that the Himalayan front has sequentially migrated southwards giving rise to new thrusts 1–3 . It is also believed that the newly formed thrusts are the focus of tectonic convergence as seen in the case of HFT at a number of places, all along its strike 4–6 . Con- sequently, many or almost all of the thrusts/faults that lie to the north of the HFT may have, at some time in the geological past, ceased to absorb the convergence of the Indian and Eurasian plates and were rendered inactive. In