SOUTH-WESTERN PORTION OF KARACHI COLLECTORATE. 187 



are peculiar in appearance, there being- a great admixture of silty and 

 marly beds; and marine layers with oysters, &c, being 'of common 

 occurrence. In all probability these silty and marly beds are the 

 same as those already noticed as occurring east of Karachi, and as 

 resembling certain rocks of the Makran group. Amongst these Man- 

 chhar beds, north of Karachi, there are great irregularities of stratifi- 

 cation ; beds of soft sandstone, for instance, resting upon silty shale or 

 marl, irregularly-shaped masses of which project from the surface of 

 the lower bed into the material of the upper. These peculiarities may be 

 due to deposition in a variable area, at one time subjected to river action 

 at another to marine. 



A part of the Native Infantry lines in the Karachi cantonment stands 



upon post-tertiary conglomerate, and the low hills 

 Hills about Matrani • « ji v , .,-,,, 



H. s. and Saphura. east ot tne lmes are capped with the same. Along 



the road, east of the town of Karachi, grits resem- 

 bling those of the Manchhar group are intercalated with high Gaj beds. 

 The latter crop out to the east of the town ; they are seen in the neigh- 

 bourhood of the hill road to Sehwan, and they form the hills of Matrani 

 and Saphura. They consist of yellow, brown, or buff-coloured limestones 

 very largely composed of organic fragments, and contain many of the 

 usual fossils, such as Operculina, spines and fragments of Echinoderms, 

 Balanus, Venus granosa, &c. Some of the beds are sandy, and the pro- 

 portion of arenaceous ingredients increases in the lower beds. In the 

 latter, which are seen in some of the ravines, are dark-coloured 

 ferruginous beds, and beneath these again are soft brown sandstones 

 impregnated with salt. The limestones and calcareous sandstones furnish 

 the building stone used in Karachi, and of this rock the church and 

 other public edifices are constructed. 



Near Saphura Landi, the first camping ground from Karachi on the 



Sehwan hill road, the Manchhar beds come in, but 

 Plain near Saphura. 



they are, as usual, much concealed by the immense 



spread of post-tertiary conglomerate. The surface of the ground is 



generally sandy. Near Saphura, the pebbles in this conglomerate are 



( 187 ) 



