TRANSACTIONS OF SECTION ©. 395 
tract occupied by this formation is confined to the immediate neighbourhood of 
the Drakensberg Range, widening out considerably in the south-west over what is 
known as the Stormberg area. 
The Stormberg series is subdivided as follows, in downward succession :— 
(4) Volcanic Beds, 
(3) Cave Sandstone, 
(2) Red Beds, 
(1) Molteno Beds, 
The strata lie nearly horizontally, or are only inclined at low angles, consequently 
the lower divisions crop out along the foot of the mountain ranges, while the upper 
beds form all the higher ground. ‘lhe Molteno Beds consist of a thickness of from 
1,000-2,000 ft. of sandstones, with thin, dark shales and mudstones and occasional 
coal-seams, Arenaceous material is predominant, and the sandstones vary from 
fine-grained grey felspathic varieties to coarsely-crystalline ‘ glittering ’ sandstones, 
with small pebbles of vein-quartz. Boulders of bard white or brownish quartzite, 
derived evidently from the Cape Formation, are common, usually scattered irregu- 
larly throughout the sandstone beds, but occasionally forming conglomerate bands. 
The coals are thin, and contain from 15 to 30 per cent. of ash, but are the only 
workable deposits in the Cape Colony. Fossils are almost entirely those of plants, 
e.g. Thinnfeldia, Taeniopteris, Callipteridium, &c., from which the Rheetic age of 
the beds has been deduced. ; 
The Red Beds are more argillaceous in character, and consist of from 600- 
1,600 ft. of strata, in which red and purple shales, mudstones, and sandstones are 
predominant, though thick beds of fine-grained, white sandstone are also common. 
Fossil remains are chiefly those of carnivorous dinosaurs, such as Huskelesaurus and 
Massospondylus. 
The Cave Sandstone is a thick bed of fine-grained felspathic sandstone, usually 
white or yellowish in colour, and of very striking appearance. As a rule, it is 
unbedded throughout, except towards its summit, or less commonly towards its 
base. In some places it attains a thickness of 800 ft., but as a rule it varies from 
160 to 350 ft. In a few places the Cave Sandstone is entirely absent, and the 
voleanic beds rest directly upon the red beds. The Cave Sandstone weathers 
into most fantastic outlines, and gives rise to very peculiar scenery along the 
Drakensberg. 
The sediments of the Karroo System were deposited in a great inland sea, ‘ the 
Karroo Lake,’ in which the water was either fresh or slightly brackish, and not 
very deep. During the formation of the Stormberg rocks the shore-line stretched 
where the coast ranges of the south of the Colony now rise, and extended east- 
wards into the Indian Ocean, and then north-eastwards parallel to the coast-line 
of Natal. This old land surface was formed of rocks belonging to the Cape and 
Pre-Cape Systems, quartzites, granites, and metamorphic rocks. 
During Cave Sandstone times volcanoes came into existence, and great erup- 
tions of basic lavas took place. Over 100 yoleanic necks have been mapped by the 
Geological Survey, some of which are over a mile in diameter, Many of the pipes 
are filled with siliceous breccias, or with tine-grained sandstone-like tuffs. The 
erupted material consists almost entirely of basic lavas, compact to vesicular, the 
most interesting variety of the latter being the ‘pipe-amygdaloid’; enstatite- 
andesites occur in a few places. Beds of volcanic ash are met with in Barkly 
East and around Jamestown. Inthe former district there are frequent alternations 
of lava, ash, and sandstone, the even bedding and passage of sandstone into ash, 
either laterally or vertically, pointing conclusively to sub-aqueous eruptions. The 
later flows were probably sub-aerial. 
At the close of the volcanic outbursts, after from 2,000-5,000 ft. of lavas had 
been erupted, the area was affected by gentle folds by which the direction of flow 
of the Kraai and Orange Rivers was determined, Then followed the gigantic and 
extensive intrusions of dolerite, which at the present day form such a conspicuous 
feature in the scenery of the Karroo. 
The interior of the colony was intermittently elevated, and the old land surface 
