page_title: Table Mountain
section_title: Geology
hierarchical_section_title: Table Mountain / Geology
caption_attribution_description: English: SkySat satellite image of Table Mountain in Cape Town, South Africa
context_page_description: Table Mountain is a flat-topped mountain forming a prominent landmark overlooking the city of Cape Town in South Africa. It is a significant tourist attraction, with many visitors using the cableway or hiking to the top. The mountain forms part of the Table Mountain National Park, and part of the lands formerly ranged by Khoe-speaking clans, such as the!Uriǁʼaes. It is home to a large array of mostly endemic fauna and flora.
context_section_description: The upper approximately 600-metre (2,000 ft) portion of the one-kilometre-high (0.62 mi) table-topped mountain, or mesa, consists of 450-510 million years old (Ordovician) rocks belonging to the two lowermost layers of the Cape Fold Mountains. The uppermost, and younger of the two layers, consists of extremely hard quartzitic sandstone, commonly referred to as "Table Mountain Sandstone" (TMS), or "Peninsula Formation Sandstone" (as it is known as at present), which is highly resistant to erosion and forms characteristic steep grey crags. The 70-metre-thick (230 ft) lower layer, known as the "Graafwater Formation", consists of distinctively maroon-colored mudstones, which were laid down in much thinner horizontal strata than the Table Mountain Sandstone strata above it. The Graafwater rocks can best be seen just above the contour path on the front of Table Mountain, and around Devils Peak. They can also been seen in the cutting along Chapman's Peak Drive. These rocks are believed to have originated in shallow tidal flats, in which a few Ordovician fossils, and fossil tracks have been preserved. The overlying TMS probably arose in deeper water, either as a result of subsidence,  or a rise in the sea level. The Graafwater rocks rest on the basement consisting of Cape Granite. Devil's Peak, Signal Hill, the City Bowl and much of the "Cape Flats", however, rest on heavily folded and altered phyllites and hornfelses known informally as the Malmesbury shales. The Cape Granite and Malmesbury shales form the lower, gentler slopes of the Table Mountain range on the Cape Peninsula. They are of late Precambrian age, pre-dating the "Graafwater rocks" by at least 40 million years.
  The basement rocks are not nearly as resistant to weathering as the TMS, but significant outcrops of the Cape Granite are visible on the western side of Lion's Head, and elsewhere on the Peninsula (especially below Chapman's Peak Drive, and The Boulders near Simon's Town). The weathered granite soil of the lower slopes of the Peninsula Mountain range are more fertile than the nutrient-poor soils derived from TMS. Most of the vineyards found on the Cape Peninsula are therefore found on these granitic slopes of the Table Mountain range.
  The mountain owes it table-top flatness to the fact that it is a syncline mountain, meaning that it once was the bottom of a valley (see diagram on the right). The anticline, or highest point of the series of folds that Table Mountain was once part of, lay to the east, but that has been weathered away, together with the underlying softer Malmesbury shale and granite basement, to form the "Cape Flats". The "Cape Flats" form the isthmus that connects the Cape Peninsula to the Mainland. The Fold Mountains reappear as the Hottentots-Holland Mountain range on the mainland side of the "Cape Flats". What has added to the mountain's table-top flatness is that it consists entirely of the very hard, lower layer of the Table Mountain Sandstone Formation. Originally this was topped by a thin glacial tillite layer, known as the Pakhuis Formation (see the diagram above, left), above which was the upper layer of Table Mountain Sandstone. Both these layers, but especially the tillite layer, are softer than the lower layer of Table Mountain Sandstone.  When these softer layers eroded away, like a cream-topping on a cake, they left a very hard, flat erosion-resistant quartzitic sandstone platform behind which, today, forms Table Mountain's top.
  Table Mountain is the northernmost end of a 50-kilometre-long (30 mi) and roughly six-to-ten-kilometre-wide (4 to 6 mi) Cape Fold Mountain range that forms the back bone of the Cape Peninsula, stretching from the Cape of Good Hope in the south to Table Mountain and its flanking Devil's Peak (to the east) and Lion's Head-Signal Hill (to the west) in the north. Table Mountain forms the highest point of this range. The range runs parallel to the other Cape Fold Mountain ranges on the mainland to the east.
caption: Satellite image of Table Mountain, surrounded by Cape Town
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