|System||Series||Stage||Age (Ma)||European lithostratigraphy|
|Bunter or Buntsandstein|
|Major lithostratigraphic units of northwest Europe with the ICS's geologic timescale of the Triassic.|
The Lias Group or Lias is a lithostratigraphic unit (a sequence of rock strata) found in a large area of western Europe, including the British Isles, the North Sea, the low countries and the north of Germany. It consists of marine limestones, shales, marls and clays.
In the past, the name Lias was often not only used for the sequence of rock layers, but also for the timespan during which they were formed. It was thus an alternative name for the Early Jurassic epoch of the geologic timescale. It is now known that the Lias is Rhaetian to Toarcian in age (over a period of ca. 20 million years between 200 and 180 million years ago) and thus also includes a part of the Triassic. The use of the name "Lias" for a unit of time is therefore slowly disappearing.
In northern Germany, the Lias Group consists of nine formations (from top to base):
- Posidonia Shale
- Arieten Sandstone
- Liassicus Sandstone
- Psilonoten Sandstone
- Gradstein, F.M.; Ogg, J.G.; Smith, A.G. (2005), A Geologic Time Scale 2004, Cambridge University Press, ISBN 9780521786737
- Somerset Geological TimeLine, fossilgalore.com
- See for example Wong (2007)
- Deutsche Stratigraphische Kommission (eds.): Stratigraphische Tabelle von Deutschland 2002 (stratigraphic tables of the German commission on stratigraphy), Potsdam 2002, ISBN 3-00-010197-7 (PDF: 6,57 MB)
- Wong, Th.E., (2007): Jurassic, in: Wong, Th.E.; Batjes, D.A.J. & Jager, J. de (eds.): Geology of the Netherlands, Royal Netherlands Academy of Arts and Sciences, pp. 107–125.