A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Hire, Pramodkumar S.
- Palaeohydrological Reconstructions Based on Analysis of a Palaeochannel and Toba-Ash Associated Alluvial Sediments in the Deccan Trap Region, India
Authors
1 Department of Geography, University of Pune, Pune - 41 1 007, IN
2 Department of Geography, S P College, Pune - 411 030, IN
3 Department of Geography, HPT/RYK College, Nashik - 422 005, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 64, No Spl Iss 4 (2004), Pagination: 481-489Abstract
The Pleistocene-Holocene palaeohydrological and palaeoenvironmental conditions of the Deccan Trap rivers are not Well-Established. This is mainly on account of the limited extent of alluvial deposits and scarcity of palaeochannels to estimate former river discharges. This paper reports the results of recent investigations it a palaeochannel and the Volcanic-Ash associated alluvial materials at two sites located in the Semi-Arid parts of the Deccan Trap region. The palaeochannel is preserved in, and defined, by the volcanic ash. The ash is believed to be associated with the 74 ka Toba Mega-Eruption.The geometry of the palaeo and modern channels were determined by undertaking EDM surveys. The mean, maximum and bankfull discharges of the palaeo and modern channels were estimated on the basis of published relationships between discharge and channel dimensions. The estimates indicate a bankfull discharge of about 15-40 m3s1 for the palaeochannel and between 600 and 900 m3s1for the modern channel. The estimates suggest that modern discharges are higher by about one order of magnitude.Stratigraphical studies at the sites show that the ash layer is often associated with thick black clays, referred to as fissured clays, which belong to marine isotope stage 3 andior 4 On the basis of modern analogs it was inferred that the Ash-Associated fissured clays represent sediments of seasonal, Low-Energy wetlands. The sedimentological characteristics indicate that during and after the Toba event the monsoonal climate was drier and river discharges were depleted. This inference is also supported by estimated mean and maximum discharges passing through the Kukadi Palaeochannel. We infer that at the time of the Toba event, which occurred during marine isotope stage 5-4 transition, the monsoon discharge and rainfall were much lower than the present in the Deccan Trap region.
Keywords
Palaeochannel, Fissured Clays, Palaeohydrology, Palaeoclimate, Deccan Traps.- The Sandan Slot Canyon in the Deccan Traps:Its Morphology and Mode of Origin
Authors
1 Department of Geography, HPT Arts and RYK Science College, Nashik 422 005, IN
2 Department of Geography, RNC Arts, JDB Commerce and NSC Science College, Nashik 422 101, IN
3 A6 Manmohan Society, Karvenagar, Pune 411 052, IN
Source
Current Science, Vol 117, No 11 (2019), Pagination: 1892-1896Abstract
Slot canyons, with extremely small width–depth ratios, are rare geomorphic features that develop under limited range of fluvial conditions. We report the occurrence of such an uncommon canyon, developed on the crest of the Western Ghats in the Deccan Traps. The canyon is a tourist hotspot. Geomorphic studies reveal that the Sandan slot canyon is 2–30 m wide and up to 100 m deep. Based on compelling field evidence we hypothesize that the morphology of the slot canyon is the product of the interplay between flash flood-induced excavation of a dyke and slope failures.Keywords
Dyke, Flash Flood, Slot Canyon, Slope Failure.References
- Richardson, K. and Carling, P. A., A typology of sculpted forms in open bedrock channels. Geol. Soc. Am. Spec. Pap., 2005, 392, 108.
- Wohl, E. E., Thompson, D. M. and Miller, A. J., Canyons with undulating walls. Geol. Soc. Am. Bull., 1999, 111, 949–959.
- Ji, S., Canyons of sculpted rocks: Geographical wonders created by flowing water. Chin. Natl. Geogr., 2018, 693, 135–151.
- Sanders, D., Wischouniga, L., Gruber, A. and Ostermanna, M., Inner gorge–slot canyon system produced by repeated stream incision (eastern Alps): significance for development of bedrock canyons. Geomorphology, 2014, 214, 465–484.
- Kale, V. S., Atlas of Geomorphosites of Maharashtra, Indian Institute of Geomorphologists, Allahabad, 2018, p. 76.
- Carter, C. L. and Anderson, R. S., Fluvial erosion of physically modeled abrasion-dominated slot canyons. Geomorphology, 2006, 81, 87–113.
- Whipple, K. X., Hancock, G. S. and Anderson, R. S., River incision into bedrock: mechanics and relative efficacy of plucking, abrasion and cavitation. Geol. Soc. Am. Bull., 2000, 112, 490–503.
- Baker, V. R. and Costa, J. E., Flood power. In Catastrophic Flooding (eds Mayer, L. and Nash, D.), Allen and Unwin, London, UK, 1987, pp. 1–21.
- Kale, V. S., Geomorphic effects of monsoon floods on Indian rivers. Nat. Hazards, 2003, 28, 65–84.