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Unpredictable Himalayan Climate
|by V. K. Joshi (Bijji)|
Forty-nine years ago around mid-November I stood gazing at the picturesque Saryu and Ramganga Rivers at Rameshwar- Ghat, now in Pithoragarh district, Uttarakhand. I had started my career as a geologist from this spot and never had inkling, that almost half a century later I will be writing something about this area!
After the confluence, the Saryu River flows along a thrust plane (a large dimension fault) that separates Thalkedar Limestone on the north from the crystalline rocks on the south. It is this limestone which matters most for this area − though the people do not know its significance. Limestone imperceptibly dissolves in water and often caves are formed in such terrains. During rains, when surface water percolates to these caves the limestone rich drops create stalagmites and stalactites. There are many such caves in this area and have begun attracting the speleologists and geologists alike, for the fascinating stalagmites and the climate records contained therein.
Dharmanjali cave is yet another such cave in this area at an altitude of 2200 m. in Thalkedar Limestone. It was studied by Jaishri Sanwal, C. Rajendran and Kusala Rajendran of Centre for earth Sciences, Indian Institute of Science, Bangalore; Bahadur Singh Kotlia of Centre for Advanced Study in Geology, Kumaun University, Nainital; Syed Masood Ahmad of NGRI, Hyderabad and Mike Sandiford of Department of Geological Sciences, University of Melbourne, Australia.
Conditions became wetter and wetter between 210 AD and 810 AD. But during this wet period there were many dry events, with each event lasting as long as ten years. From 830 AD to 910 AD, nearly for a century there was a very wet period. This period incidentally coincided with the lower part of what is called by the paleo-climatologists as the Medieval Warm Period (MWP-approximately from around 900 AD to 1300 AD). More water means increased solution of calcium carbonate and that leads to greater deposition of stalagmites-a fact confirmed by these researchers from Dharmanjali cave.
The Indian Summer Monsoon, due to its elusive nature requires an in depth study and refinement. It is said that ‘Present is a key to the past and the past is the window for future’, that is why it makes sense to study the past, may be even from proxy evidences to know it better.
Image of Saryu and Ramganga confluence at Rameshwar-Ghat, November 1964
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