Page 123 - Bulletin 11 2007

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THE GEOLOGY OF BUILDING STONE AND QUARRIES
IN THE SOUTH PENINSULA

Doug Cole

Introduction

Numerous buildings between Muizenberg and Simon’s Town are constructed of local

stone and it is the purpose of this article to describe the nature, origin and distribution of
this stone, the quarries from which it was exploited, and examples of where it was used.

Figure 3.1 is a simplified geological map of the South Peninsula derived from Theron

(1984a) and Figure 3.2 is a geological cross-section through the South Peninsula from
Chapman’s Peak to Muizenberg. Five abandoned quarries, which produced limited

quantities of building stone, are situated on the False Bay side of the Peninsula between

Lakeside and Simon’s Town. (Fig. 3.1). There are no quarries in the western side of the
Peninsula and the description is therefore focussed on the eastern side.

Geological History

The oldest rock in the South Peninsula is granite of the Cape Granite Suite, which has

been dated at 540 million years using uranium/lead isotopes of zircon. (Armstrong et

al., 1998). Zircon is an accessory mineral of the granite that crystallised from the
original liquid magma. (Theron, 1984b). The granite is found along the coast and in the

Fish Hoek Valley and forms a pedestal below the sandstone-dominated Table Mountain
Group. (Figs. 3.1 and 3.2). The granite intrudes slate of the Malmesbury Group between

Rondebosch and Sea Point, with the slate representing metamorphosed clay and silt that
were deposited in a deep ocean about 600 million years ago.

The Table Mountain Group consists of a lower interbedded sandstone, mudstone and
siltstone unit, the Graafwater Formation, between 25 and 65 m thick, and an upper