An Encyclopaedia of Indian Archaeology v1.c14.s2.19

v1.c14.s2.19

5. The later part of the Upper Pleistocene was a period of extreme aridity when strong aeolian activity took place, covering a considerable part of the alluvial plain with sand. A ¹⁴C date of *c.* 40000 B.P. from the base of the aeolian bed in a 4 m thick sequence of alternating fluvial and aeolian sediments near Tibna village, 15 km e. of Shergarh in Jodhpur, gives some idea of the age of this aridity. The source of the sand was the fine alluvial silty sand of the aggraded plain. Our extensive observations show that there is a very close relationship between the location of dunes and the availability of sand. Rocky and gravelly plateaux and plains with no source of sand supply in their close vicinity are completely free from dunes; on the other hand, alluvial plains with ample supply of fine sand are thickly covered with dunes. There is very little evidence to support the oft-repeated theory of the Rann of Kutch being the principal source of sand for the dunes of Rajasthan. This period was not however throughout uniformly arid; rather it was interrupted by several wet phases. A ¹⁴C date of *c.* 26000 B.P. from Malhar lake shows that the lake was carrying fresh water at this time. Similarly, in the Didwana lake below the sediments dated to *c.* 10000 B P there are several m thick sediments marked by alternating layers of sand, silty clay and a thick bed of salt, suggesting a very unstable climate before the Holocene. The alternating fluvial and aeolian sediments in the Tibna section referred to above also suggest a fluctuating dry and wet climate. The formation of a thick layer of calcium carbonate within the dune sand in the railway cutting at Didwana also suggests a wet episode during an otherwise long dry period.