What is Lower Jurassic?
[[File:Blue lias cliffs at Lyme Regis.jpg|thumbnail|300px|[[Blue Lias]] cliffs at Lyme Regis, [[Dorset]]]] The '''Lower Jurassic''' is the first [[geology|geological]] [[Epoch (geology)|epoch]] in the [[Jurassic]] that began 201.3 [[million]] years ago, and ended at 174.1 million years ago. The Jurassic period is divided into Lower, Middle and Upper. The Lower Jurassic started after the [[end-Triassic extinction event]] at 201.3 million years ago (mya). Its rocks form in Europe the ''Lias'' group of marine [[strata]] consisting mostly of [[limestone]], with some [[clay]]s and [[siltstone]]. It was in this formation on the [[Dorset]] [[Jurassic Coast]] that [[Mary Anning]] did much of her work. The mudstones of the earliest Jurassic (Blue Lias) give way to carbonate rocks as the water deepens in the [[Middle Jurassic]]. The [[Jurassic]] [[period]] was one of the time periods when [[dinosaur]]s were on the [[Earth]]. By this time, many groups of the [[Triassic]] period had become extinct. == Britain == At the start of the Jurassic, Britain was warm [[temperate]] to [[subtropical]], between 30° and 40° north of the [[equator]]. Temperature would have been in the range of 12–29°C. Shallow seas were over southern England; higher ground like the [[Mendip Hills]] were a string of islands stretching westwards South [[Wales]]. == North America == [[Image:SEUtahStrat.JPG|thumb|300px|The [[Permian]] through [[Jurassic]] stratigraphy of the [[Colorado Plateau]] area of southeastern [[Utah]] that makes up much of the famous prominent rock formations in protected areas such as Capitol Reef National Park and Canyonlands National Park. Photograph from Glen Canyon National Recreation Area, Utah.]] The Lower Jurassic in western [[North America]] is quite different. It is continental in origin, [[sandstone]]s laid down in shifting [[stream]]s and [[river]]s. These sandstones were laid down over a long period from the later [[Permian]] to the Lower Jurassic. == Related pages == *[[Blue Lias]] *[[Jurassic]] *[[Middle Jura