The mountains around Barberton are amongst the oldest in the world, dating back 3.5 billion years, and these mountains include some of the oldest exposed rocks on the planet. These volcanic rocks, which scientists call the Barberton Greenstone Belt, have given direct evidence of the conditions of life on the surface of the very early Earth.
In the satellite image, the bare rocks of mountain peaks appear as a pale gray-green, accentuated by the sharp relief of sunlit slopes and their shadows. Deeper shades of green indicate vegetation, including some vegetation on the lower slopes. In the mountain valleys, bright green areas suggest well-watered grassy areas and crops. Deeper green areas are probably forests. The series of bright green circles north of the town of Barberton result from centre-pivot irrigation systems. The area north and west of Barberton appears slightly pale and fuzzy compared to the rest of this image, probably the result of low-lying haze.