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Geology

Mayotte is a primarily volcanic island rising steeply from the bed of the ocean to a height of 660 metres (2,170 ft) on Mont Bénara (OpenStreetMap gives this as 661 metres (2,169 ft)).

Two volcanic centres are reported, a southern one (Pic Chongui, 594 metres (1,949 ft)) with a breached crater to the NW, and a northern centre (Mont M'Tsapéré, 572 metres (1,877 ft)) with a breached crater to the south-east. Mont Bénara is on the curving ridge between these two peaks, approximately at the contact point of the two structures. Volcanic activity started about 7.7 million years ago in the south, ceasing about 2.7 million years ago. In the north, activity started about 4.7 million years ago and lasted until about 1.4 million years ago. Both centres had several phases of activity. The most recent age reported for an ash band is 7000 year BP.