Geology of the Cape Peninsula - South Africa

Nature Talk
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Hey

Can any geology fundi’s tell me, what is the dominant sedimentary formation in the Cape Peninsula? In my view it can either be one of these 3:

Sandstone
Calcareous sandstone
Limestone

For all my observations on the Peninsula thus far, I have classed the geology of the terrain as limestone, but now I’m not sure

The soil in the rockies of the central Peninsula, particularly the higher altitude area’s, is white, and has the same consistency and texture as fine beach sand. It does not form flat to mildly undulating ‘pavements’ like it does in Natal province (sandstones), but rather a series of patchy and uneven ‘koppies’ and levies. However, in some area’s, the rocks show incipient crystallization, some of which implies the presence of silicate minerals and submergence under water/ waterlogged land for a long period, which implies Sandstone origins

Any thoughts?

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It’s sandstone sitting on top of granite.
https://en.wikipedia.org/wiki/Cape_Peninsula#Geology

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Or Table Mountain Sandstone on Malmesbury shale. Depending in which side of that divide you are on.

Limestone fynbos on the Bredasdorp Formation.

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You made me curious about
Agulhas Limestone Heathland

which I found here
https://www.opengreenmap.org/greenmap/cape-town-green-map/macassar-dunes-conservation-area-3521
Agulhas limestone fynbos occurs on hard calcrete outcrops on the dune summits and upper slopes

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And that limestone explains why, each year, people ask about the dividing line in the water of False Bay - from the chalk swirling in the seawater.

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Thanks

The Table Mountain Sandstones stretch east all the way into Natal too, but those formations look vastly different to what we get here, in both the topographical and composition sense

…so what would give our sandstones here in the Peninsula such a white and bleached out colour? :thinking:

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Higher Calcium Carbonate content?

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Maybe more quartz? But I don’t have enough geology to answer you. Up on the Groot Winterhoek mountains the sand is a dazzling white!

Depending on where you are, you can also see much darker minerals leaching out along the cracks in light sandstone.

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