Lysurn—WMining and Minerals in the Transvaal, ete. 13 
by the prospector as the guides to the location of 
the Main-reef series, prospectors maintaining that the 
Main-reef lies at a distance varying from 12 to 14 
miles south of these shales. Many similar beds are 
to be met with west of Johannesburg. 
II.—The Banket (= puddingstone in Dutch) series, embracing 
the sandstones, quartzites, and conglomerate beds of 
the Witwatersrandt, may be sub-divided into—1, the. 
Main-reef series; 2, the Bird-reef series; 3, the 
Kimberley series; 4, the Elsburg series. 
IIt.—The Black-reef series. 
IV.—The Dolomitic Limestone. 
V.—The Magaliesburg series. 
1. Main-reef series.—The main-reef series mostly strike east and 
west, with southerly dip, and can be traced for about twenty- 
eight miles. At Boksburg, east of Johannesburg, the beds dis- 
appear under the coal, or Karoo formation, and reappear in the 
vicinity of Benoni, and can be followed for a distance of about six 
miles, disappearing again under the Coal-measures. Following the 
outcrop of the series where observable, the general formation is 
found to strike in the extreme east of the district north and south, 
with westerly dip. The series are seen at Heidelburg striking 
east and west, with northerly dip, thus completing a syncline. 
To the west of Johannesburg in the Krugersdorp district, the 
series are much faulted and other conglomerate beds are met with. 
The Main series consist of three productive reefs, namely, the Main- 
reef, the Main-reef leader, and the south reef, and are separated 
by sandstones of variable thickness, the distance from the Main- 
reef to the Main-reef leader varying from a few inches to 7 feet, 
and from the latter to the South reef from 30 feet to 110 feet. 
Other reefs are known to exist, but are of no commercial value at 
present. 
The thickness of the Main-reef ranges from 3 feet to 12 feet. 
The Main-reef leader from 1 inch to 3 feet, and the South reef from 
a single pebble to 5 feet 6 inches. 
The South reef is the richest ; the Main-reef the poorest. 
The conglomerates are composed of white and smoky pebbles 
presenting a waterworn appearance and are cemented by silica, 
