The caldera lies atop a shield volcano or ash cone in the southern Marra Mountains, which developed first as a pile of basaltic lava flows and later as layers of volcanic ash and tuff, including the eruptions that formed the caldera.

[9] The rim of the caldera reaches a maximum elevation of 3,024 metres (9,921 ft) in the southwest,[2] and is steep almost vertical.

[10] The caldera is cut into volcanic ash, lapilli, lavas, obsidian and tuffs, and the floor is strewn with pumice blocks.

[17] The volcanic cone has a lake as well, which is 108 metres (354 ft) deep[2] and smaller, with a roughly rectangular shape that extends in north-south direction.

[24] Around the Deriba caldera, drainage occurs either southward or westward,[25] leading into the Bahr El-Arab of the White Nile and the Chari River of Lake Chad respectively.

[6] Jebel Marra consists of a pile of mostly basaltic lava which has been covered by pumice and volcanic ash as well as pyroclastic rocks and ignimbrites.

[38] The basement is formed by crystalline rocks, mainly metamorphosed gneisses and schists,[39] and is a mobile belt of Panafrican age.

[32] They are in part covered by the Nubian Sandstones of Cretaceous age and aeolian sands,[40] and by the Jebel Marra massif which occupies a surface of 13,000 square kilometres (5,000 sq mi).

[34] Tectonic uplift of the Darfur dome commenced in the Cretaceous[41] and resulted in a noticeable upwarp of the basement beneath Jebel Marra.

[42] Volcanism in the Jebel Marra mountains appears to have begun 15 million years ago and continued in two stages, separated by an erosional period.

[41] After an initial stage, during which olivine basalt and small amounts of pyroclastic material were erupted, trachyte were emplaced.

[50] Vegetation above 2,400 metres (7,900 ft) elevation in the Marra Mountains, including around Deriba, consists of man-made grassland with scarce trees such as the wild olive.

[49] It is likely that past humid periods permitted the expansion of Mediterranean species into the Jebel Marra mountains.

[21] Copepods live in the smaller lake, while the larger one is populated by blue-green algae and rotifers.