t
sufficient to determine if the beds belong to the Devonian or
Carboniferous System.

The thickness of the rocks of the Cape System exceeds 5000 ft.

The Karroo System is _par excellence_ the geological formation of South
Africa. The greater part of the colony belongs to it, as do large tracts
in the Orange Free State and Transvaal. It includes the following
well-defined subdivisions:--

Feet.
/ Volcanic Beds . . . . 4000 \
Stormberg < Cave Sandstone . . . . 800 > Jurassic
Series | Red Beds . . . . . . 1400 /
\ Molteno Beds . . . . 2000 \
Beaufort / Burghersdorp Beds \ > Trias
Series < Dicynodon Beds > . . 5000 /
\ Pareiasaurus Beds / \ Permian
Ecca / Shales and Sandstones \ /
Series < Laingsburg Beds >. 2600 \
\ Shales / |
Dwyka / Upper Shales . . . . 600 > Carboniferus
Series < Conglomerates . . . . 1000 |
\ Lower Shales . . . . 700 /

In the southern areas the Karroo formation follows the Cape System
conformably; in the north it rests unconformably on very much older
rocks. The most remarkable deposits are the conglomerates of the Dwyka
series. These afford the clearest evidences of glaciation on a great
scale in early Carboniferous times. The deposit strictly resembles a
consolidated modern boulder clay. It is full of huge glaciated blocks,
and in different regions (Prieska chiefly) the underlying pavement is
remarkably striated and shows that the ice was moving southward. The
upper shales contain the small reptile _Mesosaurus tenuidens_.

Plants constitute the chief fossils of the Ecca series; among others
they include _Glossopteris, Gangamopteris, Phyllotheca_. The Beaufort
series is noted for the numerous remains of remarkable and often
gigantic reptiles it contains. The genera and species are numerous,
_Dicynodon, Oudenodon, Pareiasaurus_ being the best known. Among plants
_Glossopteris_ occurs for the last time. The Stormberg series occurs in
the mountainous regions of the Stormberg and Drakensberg. The Molteno
beds contain several workable seams of coal. The most remarkable feature
of the series is the evidence of volcanic activity on an extensive
scale. The greater part of the volcanic series is formed by lava streams
of gr