1876.] W. T. Blanford, — Geography of the Great Indian Desert. 14;1 



found an asylum with Maharaja Siiraj-Mall of Bliai-tj)ur. Muhiyy-ul- 

 Millat reigned for about a year. In 1174 H., lie was deposed during the 

 invasion of Ahmad Shah Durrani.' 



The following papers were read — 

 1. — On the JPhysical Geography of the Great Indian Desert, with special 



reference to the former presence of the Sea in the Indus Valley, and 



the origin and mode of formation of the Sand-hills. — By W. T. Blajs"- 



roED, Esq., F.E.S. 



(Abstract.) 



This paper commences with a notice of the wide geological distinc- 

 tions which exist between the peninsula of India and the surrounding 

 regions, and after pointing out how long these differences have j)revailed, 

 how important the zoological pecuharities of India are, and how far they 

 justify the conclusion that India was for a long period part of an Indo- 

 Af rican continent or land area, to which Australia at one time must have 

 been united, the author proceeds to call attention to the importance of 

 investigating the border regions between the Indian peninsula and the sur- 

 rounding countries. These border regions consist mainly of the Indo- 

 Gangetic jDlain in which all older formations, and all traces of geological 

 action are concealed beneath the deep alluvial deposit, and it is only in a 

 few localities that portions of these regions are free froni the alluvial cover- 

 ing. The Indian desert between the Indus vaUey and Rajputana is such a 

 tract. 



A brief description is given of the 2:>hysical character and zoology o£ 

 the desert ; it is shewn to consist of rather higher rocky ground about Jesal- 

 mir and Balmir, and lower sandy tracts along the borders of Siud and 

 towards Jodhpiir, especially in the Luni valley. The northern portion of 

 the desert has not been visited by the author, but it is said to be sandy 

 throughout. A very large portion of the area consists of sand-hills, which, 

 on the borders of the Indus valley, are arranged in long ridges running ap- 

 proximately from north-east to south-west, but elsewhere are less regular 

 in form ; they have, however, always a steep face towards the north-east, 

 and a long slope toward the south-west. At first the desert might be 

 taken for a plain of marine denudation, but the jDhysical characters of the 

 hills are opposed to this view ; the scarps seen being of subaerial origin. 



Between the sand-hills in eastern Sind are long jjools of water knoAvn 

 as ' dhandhs,' of considerable depth. Those to the westward, the water of 

 which is supplied from the Indus valley, are fresh ; to the eastward, Avhere 

 the water is supplied by percolation through the sand from the freshwater 

 " dhandhs," it becomes salter and salter, until in some lakes salt and gyp- 

 sum crystals are found. In some of the brackish water lakes a well known 



