_The Upper Keuper Sandstone_ is a thin band of sandstone, not exceeding thirty feet in thickness, which occurs irregularly in the upper part of the Keuper Marls. It is well exposed at the entrance to the canal tunnel at Shrewley Common, and in a small quarry at Rowington (thirteen miles south-east of Birmingham), and also crops out on the hill sides at many points in South Warwickshire. From this thin stratum, the Rev. P. B. Brodie, F.G.S., has obtained a fossil fish (_Palæoniscus superstes_), and the crustacean (_Estheria minuta_). Specimens of these may be seen in the Warwick Museum, which contains the finest collection of Triassic fossils possessed by any provincial museum. HOW THE TRIASSIC ROCKS WERE FORMED.--According to the writer’s views, the area now occupied by central England, alternated in condition during the Carboniferous epoch, between a low plain and a shallow sea. In the Permian period, land conditions prevailed, except in the North and North Midland Counties, where a brackish sea somewhat like the Baltic, it may be--occupied a shallow depression. In Triassic times this central sea appears to have been completely cut off from the open ocean, and to have formed a large inland lake, comparable to the Caspian or the Dead Sea of our own day. The southern boundary of this inland sea was formed by a ridge of old rocks which extended from Charnwood by Hartshill and the Lickey to the Wrekin and Malvern Hills. In the basin north of this axial ridge, all the subdivisions of the Bunter and the Keuper were in turn deposited; and the cliffs and reefs of the Palæozoic rocks of which this coastline was composed, yielded large contributions to the pebble-beds, sands and marls, which constitute the Trias. According to a theory originally advanced by Professor Hull, and ably supported by Professor Bonney, the pebbles of the Bunter were mainly derived from the Paleozoic Rocks of the N.W. and N.E., some being possibly furnished by the ancient strata of N.W. Scotland. The waters of the Triassic sea were so overcharged with salts of iron, that every grain of sand was encrusted, before its deposition, with a pellicle of peroxide of iron: of chloride of sodium (common salt) and sulphate of sodium (gypsum), there was also an excess, so that much was deposited on the sea-floor, producing beds of rock-salt and of gypsum, of considerable thickness. The presence of these mineral substances in the water was prejudicial to life, so that--as in the Dead Sea, and in Lake Utah to-day--few living creatures could inhabit the Triassic sea, and fossils are consequently of extreme rarity in strata of this age.