Been in Swaziland for the last month. A beautiful country and quite complex for such a small one. A traditional King and some of the oldest terrain on the planet. Sibebe Rock is a grand granite mountain some three billion years ago, the second largest pluton in the world. It dates to the first formation of continental crust.
From hiking through the hills here, some basic ancient history put together from various sources including my ancient geology studies: About 3.5 billion years ago oceanic basalt broke the surface in what is now southern Africa. Soon after, erosion, sedimentation, burial, heating and erupting began producing granite. By 3 billion years ago, enough granite had been extruded – and added with metamorphic gneiss also so produced – to form the root of a continental pluton. The Swaziland Supergroup of the Barberton Greenstone belt contains some of the oldest-known, least-metamorphosed sedimentary and volcanic rocks on Earth. Chert is the most abundant sedimentary rock type within the volcanic part of this mix. The oceans then were about 100oF degrees warmer than present. During this time – 3.5 to 3.3 bya – bacteria, including cyanobacteria, formed stromatolites “commonly low-relief, nearly stratiform, laterally linked domes … [and some] pseudocolumns and crinkly stratiform stromatolites … on a substrate of altered komatiitic lava [lava with high iron-nickel-copper-platinum-group content from an erupting komatiite volcano] and sediments deposited on the lava surface, and in most places … covered by later komatiitic flows. Abundant fine-grained tourmaline included within the stromatolite laminae suggests that stromatolites formed in an environment dominated by boron-rich hot-spring emissions and evaporitic brines.” Picture the hot springs of Yosemite on a larger scale and perhaps on the shore of an ocean.
Much later, apes turned into humans in the same area and the humans made some of their first tools with that chert.
Southern Africa Fossil Stromatolite