Ancient Gneiss Complex

geological region, Eswatini

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June 18, 2026

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The Ancient Gneiss Complex, located in Eswatini (formerly Swaziland), is a geological region composed of granulites and gneisses. These rocks were subjected to high-grade metamorphism deep within the Archean crust, at temperatures between 750–980 °C and depths of 15–30 km. This complex represents a section of the ancient continental crust that has been significantly uplifted and eroded.12

Granulite-gneiss belts like the Ancient Gneiss Complex are characterized by extreme structural complexity due to multiple deformation events. They are thought to have formed from the interthrusting of oceanic crust basalts, limestones, sandstones, shales, and granites from continental margins. These belts are found in various locations globally, often surrounded by younger rock formations. The age of these belts can range from over 4 billion years old to 2.5 billion years ago, representing a significant portion of Earth's geologic history.12

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Precambrian
Structure and occurrence of granulite-gneiss belts
…small areas such as the Ancient Gneiss Complex of Swaziland, the Minnesota River valley and the Beartooth Mountains of the United States, the Peninsular gneisses and Sargur supracrustals of southern India, the English River gneisses of Ontario in Canada that form a
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…small areas such as the Ancient Gneiss Complex of Swaziland, the Minnesota River valley and the Beartooth Mountains of the United States, the Peninsular gneisses and Sargur supracrustals of southern India, the English River gneisses of Ontario in Canada that form a
Read More