GEOLOGY OF THE SOUTH AFRICAN REPUBLIC 9 
were formed from the carbon in the shale through the agency of 
the intruded eruptive rocks. 
Near the Witwatersrand the coal-bearing beds transgress 
horizontally over the upturned edges of the auriferous conglom- 
erates, and coal mines are worked at Bocksburg, Brakspan, Oli- 
fants River and other points within 12 to 20 miles of Johannes- 
burg. The coals are gas, coking, blacksmith and steam coals, 
all varieties being sometimes found ina single district. Beds 
up to 20 feet in thickness occur. Dunn speaks of an anthra- 
cite vein intersecting the Karoo beds vertically at Buffel’s Kloof 
in Cambedoo. Semi-anthracites are found, according to Schmeis- 
ser, in Bocksburg and Brakspan, which have a high percentage 
of ash. The ash from that of the former place, tested by Pro- 
fessor Stelzner, yielded to the assay $4.50 per ton in gold. 
Remains of Labyrinthodonts (amphibia), and Dicynodont 
(few-toothed) and Oudenodont (toothless) reptiles from these 
beds have been described by Owen and Huxley. Both Equisete 
and Glossopteris occur inthe lower Karoo beds, according to Dunn. 
This peculiar fauna, and more particularly the Glossopteris flora, 
which apparently was only developed in the southern hemisphere, 
has called the attention of paleontologists especially to these beds. 
Schenck says that the fossil flora of South Africa, especially the 
characteristic 7innfeldia odontopteroides, stands in connection with 
that of the Argentine republic in South America, with the Rads- 
chmahal beds of India, the Hawkesbury and others of Australia, 
and those in the Jerusalem basin of Tasmania. 
In most of these regions the base of the coal-bearing beds, 
in which this peculiar flora has so suddenly replaced that which 
in other countries characterizes the Carboniferous formation, 
consists of a conglomerate carrying peculiarly large, angular rock 
fragments. These features have seemed to many geologists to indi- 
cate the former presence of asouthern ice-sheet. On Dunn’s geolog- 
ical map the Dwyka conglomerate, which constitutes the lowest 
member of the Karoo formation, is called “glacial conglomerate.” 
Some earlier geologists, seeing it probably at different exposures, 
have called it claystone porphyry, others trap-conglomerate. 
