POSSIBLE MEASURES OF AMELIORATION. 



151 



shell-sand, moreover, comprises all the coarser-grained material, as may 

 be seen from the following analysis : — 





Shore. 



Sandhill 



Soluble in acid — shell-sand 



. 66-25 



. 53 - 5 



Left on sieve No. 50 . 



• 275 



• • 1 • 1 



70 . 



• - 7 - 35 



3'5 



„ 100 . 



• i7"5o 



. 3 2 "° 



Passed through 100 . 



. 6-25 . 



iro 





IOO'OO 



IOO'O 



A few grains of coal and cinder were left on the 24-mesh sieve in 

 the case of the shore sand. 



An examination of the sands under the microscope shows that while 

 the grains of the shell-sand are almost all smoothed and polished, those 

 of the insoluble residue consist, even in the case of the sandhills, of 

 angular fragments of clear quartz, mixed with a small proportion of 

 other minerals, principally a green hornblende and small flakes of mica. 



A sample of the dredgings, made of an equal mixture of each, was 

 also treated with acid, and lost 60 per cent, of its weight ; the residue 

 was then washed clear of clayey matter, which prevented its being 

 satisfactorily sieved, and lost a further 4 per cent., after which the 

 remainder was sieved, -with the following result : — 



ouiuuie in auiu — 

 Clay and very fin: 



: silt . 



# 



4-0 



Left on sieve No. 



24 • 





o-S 



a 



50 • 



• 



• 1*5 



ii 



70 . 



. 



5'9 



11 



IOO . 



. 



l6"2 



Passed through 



100 . . 



' ' 



. u-6 





IOO'O 



5. -Possible measures of amelioration. 

 Having described the mode of occurrence, form, and composition 

 of the sandhills, there remains for consideration the question of 

 whether and how far their further growth may be prevented, and the 

 amenities of Clifton kept available to the residents of Karachi. 



As has already been explained, the ground from which the sand 

 is derived is the stretch of land which has grown in front of the old 

 cliffs at Clifton, and of the old entrance to the Chinna creek. This 



( >9 ) 



