Archive for October, 2021

Thursday 21st October 2021

Posted in Uncategorized on October 21, 2021 by uppyalf

Wednesday 20th October 2021

Posted in Uncategorized on October 20, 2021 by uppyalf

Sunday 17th October 2021

Posted in Uncategorized on October 17, 2021 by uppyalf

A neat little Gryphaea from the Blue Lias outcrop of #Warwickshire’s Lower Avon Valley.

The Blue Lias is a geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassic times, between 195 and 200 million years ago. The Blue Lias is famous for its fossils, especially ammonites.

Its age corresponds to the Rhaetian to lower Sinemurian stages of the geological timescale, thus fully including the Hettangian stage. It is the lowest of the three divisions of the Lower Jurassic period and, as such, is also given the name Lower Lias. Stratigraphically it can be subdivided into three members: the Wilmcote Limestone, Saltford Shale and Rugby Limestone.

The Blue Lias comprises decimetre scale alternations of argillaceous limestone and mudstone. These alternations are caused by short-term climatic variations during the Early Jurassic attributed to orbital forcing (Milankovitch cycles). These limestone-mudstone alternations pass up into a clay member formerly known as the Lower Lias Clay now the Charmouth Mudstone. This lithology consists of monotonous mudstones weathering to clay at the surface. Sparse thin limestone and nodule bands are seen where the rocks are exposed. The deposition of a clay-rich mudstone member normally indicates deposition in a deeper marine environment. The lowest beds of the formation are referred to as the “Pre-planorbis beds” in reference them being deposited before the first appearance of the ammonite Psiloceras planorbis.

Saturday 16th October 2021

Posted in Uncategorized on October 16, 2021 by uppyalf

Friday 15th October 2021

Posted in Uncategorized on October 15, 2021 by uppyalf

Thursday 14th October 2021

Posted in Uncategorized on October 14, 2021 by uppyalf

Tuesday 12th October 2021

Posted in Uncategorized on October 13, 2021 by uppyalf

Monday 11th October 2021

Posted in Uncategorized on October 12, 2021 by uppyalf

Sunday 10th October 2021

Posted in Uncategorized on October 10, 2021 by uppyalf

Saturday 9th October 2021

Posted in Uncategorized on October 9, 2021 by uppyalf