Klerf Formation
The Klerf Formation is an Early Devonian (Emsian) formation that includes a Lagerstätte in the Northern Eifel hills, at Willwerath near Prüm, Rhineland-Palatinate, Germany. In it Jaekelopterus rhenaniae, a giant eurypterid was discovered. The Klerf Formation, comprising greenish and reddish shales, siltstones and sandstones, was first described in 1919 by Rudolf Richter (1881-1957) and reaches a maximum thickness of about 1,300 metres (4,300 ft).[1]
| Klerf Formation | |
|---|---|
| Stratigraphic range: Emsian ~ | |
| Type | Geological formation |
| Sub-units | Reifferscheid Mb. Altenberg Mb. Unterpreth Mb. |
| Underlies | Heisdorf Formation |
| Overlies | Schleiden Formation |
| Thickness | 1,300 m (4,300 ft) |
| Lithology | |
| Primary | Siltstone, shale |
| Other | Sandstone |
| Location | |
| Location | Eifel |
| Coordinates | 50°14′48″N 06°27′21″W |
| Region | Rhineland-Palatinate |
| Country | |
| Type section | |
| Named by | Richter |
| Location | Willwerath near Prüm |
| Year defined | 1919 |
| Coordinates | 50°14′48″N 06°27′21″W |
| Approximate paleocoordinates | 27.1°S 09.7°E |
| Region | Eifel |
| Country | |
![]() Avalonia with the Proto-Tethys Ocean (3) | |
Depositional environment
The siltstone and sandstone formation was deposited in an estuarine to deltaic environment.[2] This was located on the edge of Avalonia bordering the Proto-Tethys Ocean.
Fossil content

Apart from the largest arthropod, Jaekelopterus (shown on the left), found in the formation, it also preserved the fish, bryozoa, brachiopod and ostracod remains,[1] the arachnids Devonotarbus hombachensis, Xenarachne willwerathensis,[2] and Mutationella indet. and flora.[3]
