Geology of Yemen

Erosion has played a major role in Yemen's geologic history and eliminated many rock units over time.

The Wajid Sandstone is the redeposited remains of the peneplain ground surface, which formed a delta and dunes in the Permian.

Basins formed in Yemen during a warm period in the Mesozoic, depositing dark-gray and gray-black shales of the Kohlan Series at the bottom of large lakes.

The Tawilah Group is an example of Cretaceous sandy conglomerate protected from subsequent erosion by the overlying Trap Series.

Lava flows and tuff is up to 1.5 kilometres (0.93 miles) thick in the Trap Series in the southwest, while laccolith intrusions are common to the north.

Basalt flow and craters from the last 2.5 million years of the Quaternary are common near Sana'a, Dhamar and Ma'rib along with large loess deposits.