The region over which triassic rocks outcrop in England stretches across the island from a point in the south-western part of the English Channel about Exmouth, Devon, north-north-eastward, and also from the centre of this band along a north-westward course to Liverpool, thence dividing and running north-east to the Tees, and north-west to Solway Firth. In central Europe the trias is found largely developed, and in North America it covers an area whose aggregate length is some 700 or 800 miles. The beds, in England, may be divided as follows; Average Thickness. KEUPER--Red marls, with rock-salt and gypsum 1000 ft. Lower Keuper sandstones, with trias sandstones and marls (waterstones) 250 ft. Dolomitic conglomerate BUNTER--Upper red and mottled sandstone 300 ft. Pebble beds, or uncompacted conglomerate 300 ft. Lower red and mottled sandstone 250 ft. The Keuper series is introduced by a conglomerate often calcareous, passing up into brown, yellow, or white freestone, and then into thinly laminated sandstones and marls. The other subdivisions are remarkably uniform in character, except in the case of the pebble beds, which in the north-west form a light red pebbly building stone, but in the central counties becomes generally an unconsolidated conglomerate of quartzose pebbles. The following tabulated form, due to Edward Hull, Esq., M.A., shows the comparative thickness and range of the Triassic series along a south-easterly direction from the estuary of the Mersey, and also shows the thinning away of all the Triassic strata from the north-west towards the south-east of England, which Hull was amongst the first to demonstrate. THICKNESS AND RANGE OF THE TRIAS IN A S.E. DIRECTION FROM THE MERSEY. ------------------+----------------+---------------+--------------- | Lancashire | | Leicestershire Names of Strata. | and | Staffordshire.| and | West Cheshire. | | Warwickshire. ------------------+----------------+---------------+--------------- KEUPER SERIES-- | | | Red marl | 3,000 | 800 | 700 Lower Keuper | | | sandstone | 450 | 200 | 150 | | | BUNTER SERIES-- | | | Upper mottled | | | sandstone | 500 | 50 to 200 | absent Pebble beds | 500 to 750 | 100 to 300 | 0 to 100 Lower mottled | | | sandstone | 200 to 500 | 0 to 100 | absent ------------------+----------------+---------------+---------------