Trias of German type, including Muschelkalk, extends at inter vals beyond the Pyrenees to the south of Spain. Triassic rocks occur in Heligoland and there is an outlier of Upper Triassic in the south of Sweden which includes coal-bearing Keuper and marine Rhaetic. Trias with Muschelkalk extends from Silesia into Poland. In north-west Russia the beds belong chiefly to the Tartaric stage—in part only Triassic.
As in Germany (excluding the Rhaetic) the Trias of Great Britain is of continental facies. Its outcrop in England and Wales is narrow in the south-west, but expands in the Midlands and bifurcates at the southern end of the Pennines, one extension projecting into Durham, the other into Cumberland and West morland, whence it extends into parts of south Scotland. Other occurrences are found in the Western Isles and on the opposed shores of Moray firth. Denudation has removed the Trias from all but north-eastern Ireland.
No representative of the Muschelkalk has been found.
The deposits usually follow the Permian (where developed) with conformity, although minor discordances occur here and there. Tending to fill up the Permian basins, they spread, in many cases, further afield and rest upon still older their higher members often overlapping their lower divisions. The typical sequence is as follows, and is compared with that occur ring west of the Pennines: The relationship of Trias to Permian is difficult to determine. As stated elsewhere (see PERMIAN) it has been claimed that part, if not all, of the Bunter of Nottinghamshire is equivalent to a great part of the Permian Zechstein of Durham. This awaits more general acceptance or denial: what may be conceded is that probably the Lower Mottled Sandstone of South Notts may represent some of the highest Permian strata occurring farther north. The Lower Mottled Sandstone of Wirral (Chesh ire) is possibly also of Permian age, whilst there are grounds for the belief that the St. Bees Shales (correlated with the Durham Permian Marls) are transition beds and may represent, in part at least, Lower Mottled Sandstone of other areas.
The Mottled Sandstones consist typically of alternations of soft red and variegated sandstones, generally without pebbles. In Nottinghamshire and south Yorkshire the Upper group is absent. The Pebble Beds are harder red and brown sandstones,
with, in places, strong false-bedding, aeolian sand grains, drei kanter, etc. In some localities they contain abundant quartzose pebbles, probably derived from local sources now concealed. In the Midlands they form undulating country typically expressed in Cannock Chase and Sherwood Forest and furnish a first-class water-bearing horizon. In Devon is the "Budleigh Salterton Pebble-bed," with pebbles derived both from Normandy and from a northern local source. These Pebble beds were accumu lated chiefly in shallow water, but some of the coarser deposits may represent dune sands. The absence of pebbles, and the finer grade of material, makes it difficult to distinguish the Bunter of north Yorkshire and Durham from the Keuper. The St. Bees and Kirklinton Sandstones also are almost devoid of pebbles. Breccias (Brockrams) were formed continuously to the west of the Cumberland hills both before and during the deposition of the Zechstein, St. Bees Shales, and part of the St. Bees Sandstone —emphasizing the intimacy of these deposits.
Keuper deposits extend into most of the above described regions, in places slightly unconformable to the Bunter, beyond the limits of which they frequently extend, and may have local breccias at the base. Of these the best known is the "Dolomitic Conglomerate" (Bristol district), a shore-line breccia of the inland Keuper sea which gradually buried a well-dissected landscape of older rocks. It is largely composed of Carboniferous Limestone set in a dolomitic matrix, but local patches contain Old Red Sandstone. It has yielded reptiles (Thecodontosaurus, Palaeo saurus). The Keuper of Charnwood Forest, Leicestershire, con ceals mountains of which the tops only are now visible.
Typical Keuper Marl consists of rhythmic alternations of chocolate red marls, red shales and pale dolomitic sandstones (skerries). In the Midlands is the Arden Sandstone with Estheria, Hybodus, Acrodus, Labyrinthodonts and plants. The Waterstones are variegated shales and marls with soft red sandstone; whilst the Lower Keuper Sandstones are false-bedded freestones—not always present. In Worcestershire the latter have yielded scor pions, and, near Birkenhead, Cheshire, footprints of reptiles.