Magaliesberg

The Magaliesberg (historically also known as Macalisberg or Cashan Mountains) of northern South Africa, is a modest but well-defined mountain range composed mainly of quartzites. It rises at a point south of the Pilanesberg (and the Pilanesberg National Park) to form a curved prominence that intersects suburban Pretoria before it peters out some to the east, just south of Bronkhorstspruit. The highest point of the Magaliesberg is reached at Nooitgedacht, about above sea level. A cableway reaching to the top of the mountain range is located at Hartbeespoort Dam, providing sweeping views of the Magaliesberg and surrounding area. The Magaliesberg has ancient origins. Its composition is ascribed to successive geological processes over a very protracted history. Its quartzites, shales, chert and dolomite were deposited as sediments in an inland basin on top of a 3 billion year old Archaean Basement Complex, known as the Kaapvaal Craton. This process of sedimentation lasted for about 300 million years. About 2 billion years ago, a massive upwelling of molten magma resulted in what is now known as the Bushveld Igneous Complex. The enormous weight of this intrusion depressed the sediments that lay beneath and tilted the sediments along the edges so that the broken escarpments faced outward and upward, and the gentler dip slopes inward. During the same period, these sediments were fractured and igneous intrusions of dolerite filled the cracks. With the passage of time these intrusions eroded, especially on the dip slopes, forming deep kloofs or ravines providing rock-climbing potential to modern man. This large dog-leg-shaped area is now termed the Transvaal Basin and includes the lofty escarpment of the Transvaal Drakensberg overlooking the Lowveld in the eastern part of the country. Massive outpourings of igneous material–volcanic lava–of the much younger Karoo Supergroup later covered the Transvaal Basin, but this was subsequently eroded so that it only remains along the Transvaal Basin's southern rim.