| Umm Irna Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Geological formation |
| Underlies | Ma'in Formation |
| Overlies | Unconformity with Umm Ishrin Sandstone |
| Thickness | 60–70 m (200–230 ft) |
| Lithology | |
| Primary | Claystone, siltstone, sandstone |
| Location | |
| Coordinates | 31°18′N35°33′E / 31.3°N 35.55°E |
| Country | Jordan |
| Extent | Several exposures along the eastern Dead Sea coast |
| Type section | |
| Named by | Bandel & Khoury |
| Location | Wadi Himara |
| Year defined | 1981 |
| Thickness at type section | 63 m (207 ft) |
  Umm Irna Formation (Jordan) | |
The Umm Irna Formation is a geological formation in Jordan. It is found in several outcrops in Jordan in the area around the eastern shore of the Dead Sea. It is Late Permian (likely Changhsingian) in age, and is the oldest unit in the succession, overlying the Cambrian aged Umm Ishrin Sandstone Formation. The formation predominantly consists of sandstones, claystones and mudstones deposited in fluvial and lacustrine conditions. [1] The formation is of considerable paleobotanical interest, as it preserves the earliest known remains of plant groups that would become widespread during the Mesozoic, including corystosperm "seed ferns", represented by the widespread Triassic genus Dicroidium, cycads (cf. Ctenis ), conifers (which were originally suggested to be podocarps, but this was later questioned [2] ), as well as Bennettitales. [3] Other plant groups present in the formation include Noeggerathiales, gigantopterids, lyginopterids and possible ginkgophytes. [3] [4]