Triassic: seasonal rivers, dusty deserts and saline lakes

The collision of Siberia and the Kazakstan microplate with the eastern side of the Fennoscandia continent in the Permian amalgamated the last major continental fragments to produce the supercontinent Pangaea, which persisted into the Jurassic (1). During the last phases of this collision, during the latest Permian–Early Triassic, extrusion of massive amounts of flood basalts occurred in Siberia, to the east of the Urals (1816). Some have proposed this event as one of the key processes controlling the largest extinction in Earth’s history at the Permian–Triassic boundary (2601; 200).

During the Triassic, England and Wales lay beyond the western termination of the Tethys Ocean, which was divided into a northern part, the Palaeotethys, and a southern part, the Neotethys (1). Between these oceans occurred the Cimmerian terrains; several now widely separated continental fragments which had rifted from the northern fringe of Gondwana in the Permian (2273). The Triassic witnessed the northward drift of these Cimmerian terrains, and the northward subduction of the Palaeotethys, which was mostly completed by the Late Triassic.