yg blanford: geology op western sind. 



The thick upper Nari sandstones, and the still thicker Manchhars, have, 

 again, the character of fluviatile deposits, but the intervening Gaj group 

 is marine, and in part perhaps estuarine. 



Thus, throughout the tertiary series of Sind there is evidence of 

 frequent alternations of marine and terrestrial conditions, the last marine 

 beds known being of miocene date. To the northward, on the flanks of 

 the Himalayas, the tertiary marine beds tend to disappear or diminish; 

 even the nummulitic limestone, the only marine formation which appears 

 to be persistent throughout the greater part of the extra-peninsular area 

 in India, being much less developed in the Sub- Himalayan ranges than 

 it is in the neighbourhood of the Lower Indus Valley. 



8. Post-tertiary deposits. — Although by far the largest part of Sind 



is covered by sub-recent formations, the deposits 



Alluvium of Indus. ^ rf ^^ ^fensst. The greater part rf ^ 



province consists of the alluvium of the river Indus, and is a part of the 

 great alluvial tract of Northern India. The Indus alluvial deposits 

 only differ from those of the Ganges in being rather more sandy as a 

 rule, and perhaps somewhat paler-coloured. The older form of alluvium, 

 forming the " Hangar " of the Ganges,— an argillaceous earth con- 

 taining nodular carbonate of lime (kankar) and grains of iron peroxide, 



h as no t been observed in Sind. This absence may be connected with 



the facts that marine conditions appear to have prevailed in the Indus 

 valley at a comparatively recent period, whilst the Ganges valley has 

 probably been land from a remote epoch. 1 



The post- tertiary formations in the Sind hills consist of gravels, sands, 



Gravels, &c, in Sind and cla J s > wWch frequently occupy large tracts 



hills. between the ridges. Coarse gravel, often consoli- 



i For a discussion of this subject see " Manual, " Part i, pp. 393, &c. It should he 

 stated that the views above expressed as to the antiquity of land conditions in the Ganges 

 plain are opposed to the opinions of many geologists. 



The evidence in favour of marine conditions having existed in the Indus valley is 

 noticed in the Manual, p. 394. See also Jour. As. Soc. Beng., 1876, xlv, Pt. 2, p. 93 ; Rec. 

 Geol. Surv. India, x, pp. 10, 21- The observations were made in Thar and Parkar, east of 

 the Indus, and outside of the area described in the present Report. 



( n ) 



