The Great Dyke of Zimbabwe is a layered mafic intrusion of igneous, metal-bearing rock that is around 2.5bn years old. The dyke intrudes through the even older rocks of African craton, the core of oldest rocks forming the continent of Africa. This geological feature extends more than 342 miles north-east to south-west across the centre of Zimbabwe, varying from 2-8 miles in width. The southern end of the dyke is captured in this photograph. Layered mafic intrusions are usually associated with valuable metals such as chromium, nickel, copper, platinum, titanium, iron, vanadium, and tin
Photograph: ISS/Nasa
The Guardian
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