IS 76.] of tlie Great Indian Desert. 103 



The only remaining conclusion is that the sands are derived from a for- 

 mer coast-line, which no longer exists. The greatest accumulations of 

 sand are found in the lowest portions of the desert, along the edge of the 

 Indus alluvium, and in the hasin of the Luni, and it has already heen 

 pointed out that, precisely in these localities, the presence of salt in con- 

 siderable quantities renders the inference probable that arms of the sea ex- 

 tended into them at a comparatively recent date. Thus both the distribu- 

 tion of salt and the prevalence of sand-hills point to the same conclusions, and 

 it is reasonable to infer that the sea, which, at no remote period, covered the 

 Ran of Kachh, extended for a considerable distance both to the north up 

 the Indus valley and to the north-east up the basin of the Luni. 



In most countries in which sand is blown from river-beds or the sea- 

 coast, it is either blown into other river- channels or it is swept into them 

 by rain. Once in the river-channels it is again carried onward to the sea. 

 There are small sand-hills in abundance in the Indus alluvial plain, 

 but they attain no great size because the sand is always swept sooner or 

 later into some stream. The peculiarity of the desert is the absence of any 

 streams — a want due primarily to the small rainfall, but intensified of 

 course by the accumulation of sand and the consequently porous nature of 

 the soil. To the eastward in Rajpiitana, as the rainfall increases, streams 

 become more numerous and sand-hills diminish in number. In short, the 

 sands of the Indian desert appear to have been blown from an old coast-line 

 in the Indus valley, along the northern edge of the Ran of Kachh, and 

 probably in the Liini valley, by the strong south-west wind, and they remain 

 spread over the country for the want of streams to carry them back 

 to the sea. 



§ 13. Conclusions. — The conclusions to which I have been led by the 

 facts narrated in the previous paper may be thus briefly recapitulated. 



1. Within very recent geological times the Ran of Kachh was part 

 of an inlet of the sea, which certainly extended for a considerable distance 

 up the eastern edge of the area now occupied by the Indus alluvium, 

 and perhaps occupied the whole alluvial area of the Indus valley : it also in 

 all probability covered a considerable tract in the Liini basin. 



2. The central portion of the desert about Jaysalmir and Balmir was 

 not covered by the sea, but formed either an island or a promontory. As 

 the northern part of the desert, towards Bahawalpur and Bikanir, has not 

 been examined, it is uncertain whether there is any evidence of its having 

 been covered by the sea or not. 



3. The sand of the desert is mainly derived from the old sea-coast, 

 and its transport into the interior of the country is due to the south-west 

 wind. 



