Variations in Water Level of Dewar Lake,Chamoli,Central Lesser Himalaya,in the last 30 ka: Preliminary Results

A continuous 3.6 m thick core from the water logged Dewar Lake at Chamoli (Uttarakhand) was retrieved to study its depositional history. The base of the sediment core is dated as ca. 30 ka BP. Based on the variation in the grain-size percentage, the core is dominated by silt over clay and sand. With a mean grain size of 5.38φ, the sediment shows very poor sorting, finely to symmetrically skewed and mesokurtic to leptokurtic kurtosis. Variation in the textural parameters throughout the core suggests climatically influenced deposition, hence five major litho-facies are reflected in the sediment core. During the phase 1, the lake water column was perhaps decreased gradually incorporating more silt to the lake through the presence of finer silt laminations indicating required energy conditions. The phase 2 is represented by somewhat raised water level compared to the phase 1. The minimum depth achieved by the lake is exposed in facies 1. The phase 3 shows fluctuating energy conditions, whereas, phase 4 reveals stable and high energy conditions. The litho-facies 5 shows the change in climatic conditions from humid to arid.