Page 127 - Bulletin 11 2007

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Mountain Group/Cape Granite Suite unconformable contact on its south-western side
by over 100 m.

By the mid-Tertiary Period (25 million years ago), the Peninsula mountain range

already displayed its present shape (Geological Society of South Africa, 1994) and

fluvial, lacustrine and shallow marine sediments in the form of clay, sand and peat, were
subsequently deposited between Noordhoek and Kommetjie to a present depth of 50

metres. These sediments include part of the Cenozoic cover of Figure 3.1, with the
remaining cover consisting of gravelly, clayey scree and colluvium that were deposited

on the lower slopes of the mountains and windblown sand that accumulated on plains in
front of the mountains. (Fig. 3.2). The majority of these latter sediments were deposited

over the past one million years.

Nature and Use of Local Building Stone in Cape Town and the South Peninsula

The European immigrants to South Africa made use of three local stone-types for the
construction of some buildings in Cape Town. These were Malmesbury Group slate,

granite of the Cape Granite Suite and quartzitic sandstone of the Peninsula Formation.
(Cole, 2002).

Malmesbury Group slate was initially used, some of which was exploited from Cape

Town’s first quarry near Strand Street, which opened in 1660, to construct the Castle.

(Cole, 2002). The slate is robust and impervious, but is difficult to dress into regular
blocks. (Wybergh, 1932). Granite and quartzitic sandstone, both of which are hard and

resistant to weathering, gradually became more popular using loose boulders prior to the
use of quarry stone in the late 1800s. (Wybergh, 1932). Joints in the granite allowed the

extraction of building blocks. Rhodes Memorial and the Rhodes Building in St George’s
Mall are examples of buildings in which granite was used, principally being sourced

th
from Higgo Quarry in present-day Higgovale around the turn of the 20 Century.
(Cole, 2002).