At the top of the Keuper is a belt of "tea-green marls" which, in the south-western counties, pass up into fossiliferous grey shales (Sully Beds). These shales have been classed with the Rhaetic.
Gypsum and alabaster appear at several horizons, the most important occurring in the Midlands at 6o-7o and i6o ft. respec tively below the Rhaetic. They are extensively mined (Newark, Chellaston, etc.). In Cheshire and Worcestershire great beds of salt set in at lower horizons, and this mineral appears also at Puriton in Somerset. The Stanwix Shales of the Carlisle district carry gypsum, whilst those of the Isle of Man, Walney Island and Preesall, Lancashire, have deposits of rock-salt.
In Britain the Rhaetic (or Penarth) Beds usually consist of White Lias (well developed in the south-west) on dark Avicula (Pteria) contorta Shales. Certain smooth-textured White Lias limestones yield a landscape marble (Cotham) : at the top is the sun-bed or "jew-stone." At the base of the Avicula Shales is a bone-bed with fossils similar to those of Germany, including the mammal Microlestes, which is also found in the Sully Beds.
In South Scotland the Annan Sandstone is correlated with the St. Bees Sandstone, whilst in Arran the Bennan Shales and Auch
enshaw Sandstones and Shales are considered to be Bunter, and the overlying marls and shales (Levencorroch and Torr nan Uain) Keuper. At the top are grey-green marls succeeded by Rhaetic Beds. Triassic rocks occur also in Skye, Raasay and Mull breccias, conglomerates, marls and cornstones, with gypsum in the upper beds—and at Morven and Ardnamurchan (Argyll shire) and Gruinard bay (Ross-shire). There is a complete passage into the Lias here. The Trias of Elginshire south of Moray Firth contains sandstones with a reptilian fauna. That of the lower beds is allied to the Karroo forms, whilst the upper beds (Lossie mouth) contain Hyperodapedon gordoni, Ornithosuchus wood wardi, etc., which are undeniably Triassic.
In Ireland existing Triassic deposits have been largely pro tected by Tertiary basalts. Both Bunter and Keuper are repre sented (Lagan valley) very similar to that of the Cumberland coast : at Carrickfergus and Kilroot, near Belfast, rock salt is found in the Marls. Rhaetic beds with Avicula contorta, etc., link the Keuper with the Lias (Lame; Collenglen, near Belfast).