﻿358 ME. FREDERIC P. MENNELL ON THE [Aug. T 9 IO > 



a third visit in company with Mr. A. E. V. Zealley, A.R.C.S. 

 It may be stated that the beds extend east and west for many 

 miles with a northerly dip of about 65°, and that they apparently 

 exhibit a perfectly normal sequence. 1 There are three main bands 

 of conglomerate splendidly exposed in the bed of the Hunyani 

 River, and of these only the lowest is gold-bearing, Which confirms 

 the inference that they are really distinct. The lower part of the 

 series, containing these conglomerate bands, is about 500 feet thick, 

 but the total thickness, including the intercalated volcanic beds, is 

 many thousands of feet, up to the base of the overlying limestones. 

 In the west the series rests upon the Banded Ironstones, themselves 

 auriferous at the Golden Kopje (Montrose Mine). At the Eldorado 

 Mine, however, the conglomerates have apparently overlapped onto 

 the Basement Schists, and there is no ironstone exposed between the 

 former and the granite mass about 3 miles to the south. Banded- 

 Ironstone pebbles are nevertheless abundant in places, although 

 granite, granophyre, and quartz are more common as a rule. The 

 granite, it must be remembered, is not derived from the neighbouring 

 masses seen at the present day, which are intrusive. 



In the Abercorn district, also in Northern Mashonaland, and 

 possibly on the same line of strike as the Lomagundi rocks, a thick 

 series of grits with occasional pebble-bands may be the equivalents 

 of the beds already described, although they differ in general 

 appearance. They also dip northwards and have the Banded 

 Ironstone on the south, though one misses the overlying limestone of 

 Lomagundi. Much attention has recently been drawn to these beds, 

 by reason of rich gold-discoveries in them, and they strike along the 

 Mazoe Valley in the direction of Simuna, where gold was discovered 

 many years ago in the quartzites of the series. These rocks are 

 microscopically very like the ' Moine Gneisses ' of the Scottish 

 Highlands, 2 although in the field they do not present the same 

 bedded appearance. In the Sebakwe district similar conglomerates 

 occur interfolded with the Banded Ironstones, of which they contain 

 very numerous pebbles. The rock of the Riverlea Mine, which has 

 been worked for gold for some years, is identical in almost every 

 respect with that of the recent Abercorn discoveries. The Belingwe 

 conglomerates are exceedingly like those of the Eand, but appear 

 to contain very little gold, though they have been prospected. 



Generally speaking, it may be asserted that the conglomerates 

 and associated rocks form a connected series, and belong to a single 

 period. That they must be of considerable thickness seems demon- 

 strated by the fact that at Lomagundi there is no reduplication of 

 the gold-bearing horizon on which the ' Eldorado ' and ' Rowdy 

 Boys ' mines are situated, or of certain other bands with well- 

 marked lithological characters. The latter feature may also be 

 noted in the Bulawayo district. 



1 See J. W. Gregory, Addresses, etc. Rep. Brit. Assoc. 1905 (Johannesburg) 

 p. 398 & S.A. Assoc. Adv. Sci. 1905, vol. ii, p. 103 etc. 



2 See G. Barrow, Quart. Journ. Geol. Soc. vol. lx (1904) p. 400, etc. 



