Flat Stratification from a Quartzarenite Unit of Lower, Upper Proterozoic (Lower Vindhyan) Age, Larji Window, (Lesser Himalaya), Kulu District, Himachal Pradesh, India

The pink Quartzarenite Unit 3 (Q₃) of Larji Window Section (Lesser Himalaya), Kulu District, Himachal Pradesh, India, shows a lower thickness of continuous, undisturbed, uniform, horizontal laminations followed by a zone of flat stratification and this in turn by cross-bedded layers. Horizontal stratification is referred to as due to high flow regime conditions and the cross stratification to moderately shallow upper part of low flow regime conditions. Flat stratification (crenulated or wavy laminations of low amplitudes and broad wave lengths) are commonly observed in flume experiments as a function of low flow regime in shallow water formed by the migration of very small ripples or very shallow sand waves but rarely reported from the stratigraphic record. The only known two instances are from Bull Run Formation (Triassic) of Northern Virginia and Duncannon Formation (Devonian) of south-central Pennsylvania. In this connection, reporting the occurrence of flat stratification from such an ancient quartzarenite unit (Lower Upper Proterozoic) as of Larji Window may be of considerable interest from the point of view of Dynamic Stratigraphy.