SCIENCE-GOSSIP. 



GEOLOGICAL NOTES IN THE ORANGE RIVER COLONY. 



By Major B. M. Skinner, R.A.M.C 



L'. Bloemfontein, 



THE town of Bloemfontein is buili over the 

 oorthem slope of a vallej bounded on the 

 north and south by dolerite hills, open "it the east, 



Fig. l. Quarry below New Fort Kc 



and rising gently up- 

 wards on the west. A 

 w a Der- course, the 

 Bloems pruit, rising 

 among the hills to the 

 north-west of the town, 

 winds eastwards at the 

 bottom of the valley, 

 passing through the 

 town, and only contain- 

 ing water after heavy 

 rain. The town climbs 

 upwards at its northern 

 e n d w herever the 

 gentler slope at the 

 foot of the hill allows 



of standing-space for dwellings; in the gardens 

 of many of the houses dolerite boulders stand out 

 of the red sandy clay, the detrital soil of the 

 dolerite. The houses being for the most part built 

 of red brick, this colour combines with that of the 

 soil to give the impression of extreme warmth 

 when viewed from within the town, this being lost 

 from a distance, whence the corrugated iron roofs 

 form t In- most striking feature. 



Geologically the country is mainly dolerite, 

 intrusive masses of this rock forming the hills and 

 tli.' main portions of the undulations and irregi - 

 larities of tin- ground: Imt in the dongas (sform- 

 water channels) and on the slopes of the hills 

 stratified rocks may often be seen. 



North of Bloemfontein is a plateau of dolerite 

 now called Naval Hill, as the naval guns at present 



have taken up a position there ; to the wesl of this 

 is a hill of the same material, having originally 

 been pari of the same mass, but separated by 

 subsequent denudation; from tin- northern and 

 westei o faces oi this, s] urs an- given off. The 

 western hill, which may be called New Fort Kop, 

 as it has at ii> sumrnil tin- rudiments of a fort, is 

 of some interest on its southern and eastern faces, 

 as it there shows stratified rocks -non-fossiliferous, 

 Imt interesting in showing thai the dolerite, when 

 bursting through, simply split without disturbing 

 the horizontally of tin- sandstones, and 

 quently overflowed tin- strata on one of the 

 northern spurs. These strata, measuring 80 feet 

 in height, taken from a buff sandstone at their 

 base, consist first of shah--, then thin-bedded -ami- 

 stone and shale-: above these two courses of fine 

 white sandstone separated by a thin layer of slaty 

 shale are seen; then come two compact siliceous 

 layers separated by a clay shale, of these siliceous 

 layers the lower is grey with irregular white marks; 

 it is of flinty consist- 

 ency : the upp< 

 black, with conchoidal 

 fracture and white 

 streak, showing lines 

 of bedding differing 

 alternately in consist- 

 ency, this being 

 markedly shown on the 

 weathered edge. Above 

 these again come 

 shales, buff. grey. 

 ribbed black and grey 

 alternately, and very 

 sandy : while the 

 highest layer of this 

 exposure consists of tl 

 or 7 feet of sandstone, white and rather soft below, 



Fin. -2. Another View of New Four Kop. 



Fig. :'■. Qo utm o> Wi st i 



