﻿Vol. 6 1.] THE GLACIAL CONGLOMERATE IN THE TRANSVAAL. 685 



A group of boulders recently observed in the south-western corner 

 of the farm known as Bosseman's Kraal, near the Wilge River, 

 and south of the Eastern Railway-line, included the following 

 members : — One boulder of white Megaliesberg Quartzite, 8 feet 

 in diameter; one of Waterberg Conglomerate, 5 feet; three of 

 Waterberg Sandstone, each measuring about 2 feet ; two of coarse 

 red granite, measuring respectively 8 and 21 feet ; and one of 

 red-banded felsite, identical with the felsites of Rhenoster Kop, 

 measuring 18 inches. 



The greater number of boulders in the Conglomerate consist of 

 rocks of local origin, which either immediately underlie any par- 

 ticular portion of the Conglomerate or occur to the northward of it. 

 In the area shown in the map (fig. 1, p. 680), the great majority of 

 the boulders consist of hard red quartzites and conglomerates from 

 the Waterberg Formation and of the Red Granite, both of which 

 occupy large areas to the north of the Eastern Railway-line. South 

 of the ridge which is formed by the eastward extension of the 

 Megaliesberg Quartzite, this rock has furnished many boulders to 

 the Glacial Conglomerate ; while, farther south again, on the 

 Eastern Rand, many boulders are found, derived from the hard 

 quartzites and ' bankets ' of the Witwatersrand Series, together 

 with abundant boulders of chert from the Dolomite to the 

 north. 



True bedding-planes are rarely seen in the Glacial Conglomerate, 

 and then appear to be quite local. Certain zones are, however, richer 

 in boulders than others, and the rock is frequently traversed by 

 ' partings ' which divide it into rude sheets, usually lenticular, with 

 irregularly-undulating surfaces. 



With the upper portions of the Conglomerate are sometimes 

 locally associated beds of massive sandstone, and lenticular patches 

 of white and cream-coloured shales and mudstones, 

 which appear to have been deposited in ' pockets ' in the Con- 

 glomerate and to consist of the finest glacial mud. In a section 

 exposed on the banks of the Bronkhorst Spruit, immediately south 

 of the railway r line, a thickness of 6 feet of these fine white shales 

 and mudstones occurs, consisting of a succession of extremely-regular 

 laminae varying from a tenth of an inch to an inch and a half in 

 thickness. The laminae are readily separated one from the other. 

 Their surfaces are either perfectly smooth, and similar in appearance 

 and colour to that of a lithographic stone, or are covered with very 

 delicate ripple-markings, of which as many as forty may occur in 

 the space of an inch. Other markings occur which appear to be 

 due to trains of eddies, such as might be produced in a film of 

 water moving over fine glacial mud, by bigger particles lying 

 on the smooth and gently-sloping surface. I have not hitherto 

 found anything in the nature of fossils among these finely-laminated 

 mudstones, although they would be admirably adapted for the 

 preservation of vegetable-remains, such as frequently occur in the 

 shales and sandstones which succeed the glacial beds. 



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