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2 Billion Years Old (but who’s counting)

Hoggar Mtns, Algeria

The Ahaggar Mountains are in southern Algeria, 930 mi south of the capital, Algiers. The highest peak, Mount Tahat, is 9,541 ft. The range is often called Hoggar.

Hoggar Mtns, Algeria
Ahaggar Mtns, Algeria. K&C Duval photo, 1990.

The mountains are mostly composed of metamorphic rock approximately 2 billion years old, a bit older than the basement rock of Arizona. There are also several peaks that are eroded volcanic plugs.

The Ahaggar Plateau on which the mountain range sits is 210,000 square mi, about the size of Arizona and New Mexico combined.

Ahaggar Mountain Range on Google Maps
The Ahaggar Mountain Range. Google Maps image.

The area sits on the African craton. The plateau was uplifted about 300 million years ago, and the uplift was accompanied by major volcanic eruptions. The central area of the range is volcanic and includes basaltic lava flows. Shown in the picture are volcanic needles, also called organ pipes, which in some areas are up to 1,000 feet high.

The area has been inhabited for at least 8,000 years, based on the age of rock art found there. There may be a few Saharan cheetahs left in the area, but there has been no photographic evidence since 2020. There are fewer than 250 of the subspecies left in Northern Africa.

There is not much water in the range, with only a couple of permanent oases, and small rivers. The Tuareg people who inhabit the area regularly visit the few water sources.