48 



Notes, chiefly Geological, of a Journey 



[Jan. 



The hollow flat, where the diamond pits are excavated, was a low swam- 

 py plain, at the season I visited them, the lower part only containing 

 some water. Being surrounded by a bank, or rising of the soil in a 

 circular manner, it has the appearance of having been once a lake. The 

 banks are formed of the red ferruginous sandy soil, prevailing all round 

 this place ; through this plain no river or rivulet flows, and the pools 

 in its lower part dry up about the month of March; and it is then 

 the time when the excavations may be commenced, and not before. 



The few hills I could see near this place were those to the north, 

 not above two or three hundred feet above the plain, and covered with 

 underwood, interspersed with large trees. Some miles beyond these 

 hillocks runs another range of hills, loftier than the nearest ones, hav- 

 ing, however, the same direction. 



The diamond pits are in general excavated at the north end of the 

 bank that surrounds the hollow. Judging from some which were dry, 

 the deepest could not be more than 12 feet; and I observed that, 

 whatever their depth was, they never came to a hard mass of rock. 

 The strata which they penetrate during the search are — first, a grey, 

 clayey, vegetable mould, about a foot or two thick ; below this an allu- 

 vium, composed of the following pebbles, (not including the diamonds) 

 which have evidently undergone attrition, their angles having been 

 worn off : sandstone similar, to the one already described — quartz — 

 siliceous iron — hornstone— carbonate of iron — felspar — conglomerate 

 sandstone, and a prodigious quantity of kankar, or concretionary lime- 

 stone (No. 15). Of this last mentioned rock, we must say a little more 

 than of the others ; the reason is obvious — namely, that th£ gem is the 

 base of the acid in the calcarious stone. 



Besides the numerous pieces of this concretionary rock, scattered on 

 the surface of the soil, and also intermixed in large quantities in the 

 diamond alluvium, it forms regular strata, or veins we might call 

 them, in a horizontal position, both in the vegetable earth, and in the 

 diamond alluvium, precisely like flints in chalk. Many of the pebbles 

 of quartz, and hornstone are not only varnished, as it were, with a fer- 

 ruginous enduit, but it penetrates into their substance. This kankar 

 contains not a trace of quartz or any other mineral ; and that in strata, 

 in the vegetable soil and in the diamond alluvium, is more friable than 

 that exposed on the surface of the ground. 



It is in this alluvial detritus that the diamonds are found; my speci- 

 mens were taken from a heap, on the brim of the last excavation, made 

 five years ago. From this refuse, the headman told me, were obtained, 

 as many small pieces of the gem, as might fill, the hollow of the palm 

 of the hand; no other excavation has taken place since. 



All the pits are of an irregular form; generally, oblong; the head- 



