8 S. &. EMMONS 
As the most important formation, its description will be given 
last. 
Karoo formation.—Under this head are included a great series 
of beds, generally occupying a nearly horizontal position, which 
form the great central plateau or High Veldt of the Orange Free 
State, and extend into Natal on the east and Cape Colony on 
the south, leaving a comparatively narrow belt of upturned older 
rocks between their bluffs and the ocean. Its several subdivis- 
ions are variously named and classified in different places and by 
different writers. Those most commonly adopted are in descend- 
ing order: 
Volcanic. 
Cave sandstones. 
Red beds. 
Molteno beds. 
\ Karoo beds. 
| Kimberly beds. 
Ecca beds. 
Dwyka conglomerate. 
Stormberg beds, 
Beaufort beds, 
Ecca beds, 
The beds of the Karoo formation consist mainly of argilla- 
ceous, siliceous, and marly slates and sandstones, with a few lime- 
stones; they are generally much softer than corresponding rocks 
of the Cape formation, and often of variegated colors; the coal- 
bearing rocks are generally coarse-grained, light-colored sand- 
stones. The two lower of the above general divisions contain a 
Glossopteris flora (of the fern family) and are hence supposed 
to be as old as Triassic, and possibly Permian or upper Carbon- 
iferous in part. According to Hatch the coal seams are confined 
to the Molteno beds of the upper division, but Schmeisser, from 
the finding of Glossopteris remains, considers that some of the 
coal beds belong to the earlier rocks. The formation is traversed 
by dikes and sheets of greenstone and other eruptive rocks, 
especially the middle division. 
It is in volcanic necks cutting the Kimberley shales that the 
diamonds occur, and, as early as 1881, Dunn suggested that they 
