Gradings

The Barberton Makhonjwa Mountain contains the oldest well-preserved sequence of volcanic and sedimentary rocks on Earth. These highly accessible Archaean outcrops present a continuous 350 million year geological sequence, from 3 600 million years ago. The physical and chemical characteristics of these rocks are so remarkably well preserved that they provide a globally unparalleled history of the early Earth. In particular, they provide unique evidence of the formation of the earliest oceanic and continental crusts and of the initial phase of the evolution of our biosphere. The area is South Africa’s largest and most scientifically well-researched and important Greenstone Belt. The Geosites illustrate some of the earliest tectonic events and formative processes of Earth’s measurable history, including valuable clues as to the origin of life itself and include:

• basaltic lavas extruded as sub-marine tubes and “pillows‟;
• chemical sediments of black chert; volcanic lapilli (ash-ball hailstones) from Earth’s earliest volcanic eruptions;
• red and black banded iron formations created by biogenesis and precipitation;
• submarine earthquake evidence;
• spherule layers indicating earth’s earliest very large meteorite impact events;
• 3 200-million-year-old beach deposits with biomats, mud cracks, wave ripples and tidal patterns;
• volcanic processes such as felsic agglomerates, dacitic tuffs and lavas;
• komatiitic lava flows, pillow lavas, ocelli, spinnifex olivine crystals;
• buck reef chert with the fossilized environment for the genesis of life;
• large exposures of migmatites and xenoliths;
• the original type-locality for the discovery of komatiite in 1968;
• exposed pillowed komatiites, some with spinifex textures, that are the signature outcrops of the world’s most diverse Archaean Greenstone Belt.