SYNOPSIS OF THE BRITISH STRATA. 29 
and fishes in great abundance ; reptiles, (particularly of two 
extinct genera, Plesiosaurus, and Ichthyosaurus,) in immense 
numbers. Drifted wood and land plants: conifers, cyca- 
deze, &e. 
Subdivisions :-— 
1. Upper lias shale, full of saurian remains, belemnites, ammo- 
nites, &c. intercalated with the lowermost beds of the Oolite: nodules 
and beds of limestone. 
2. Lias marlstone ; calcareous, sandy, and ferruginous strata, very 
rich in terebratule and other marine shells. 
3. Lower lias clay and shale, abounding in gryphea incurva, and 
other marine shells; intercalations of sands and clays, with nodules 
of limestone. 
4. Lias rock; a series of laminated limestones, with clay partings. 
Bone-bed, with numerous remains of fishes. 
Obs.—The Lias is the grand depository of those tribes of marine 
reptiles, the Ichthyosaurt and Plesiosauri, whose remarkable forms, 
structure, and state of preservation, have excited the attention even 
of the most incurious. The collection of these remains in the British 
Museum, principally formed by Mr. Hawkins, is unrivalled.* 
Tue Trias; or New Rep Sanpstone Formation. ¢ 
(Wond. p. 533). This group of rocks consists of varie- 
gated marls, sandstones, and conglomerates, frequently of 
a red colour, with marine shells, crinoideans, fishes, and 
reptiles ; marine and terrestrial plants. This series contains 
extensive deposits of rock-salt, and brine-springs. 
This formation comprises the 7rias, or triple group, viz. 
the Keuper, Muschelkalk, and Upper Bunter Sandstein, of 
the German geologists. 
Subdivisions :— 
1. Variegated red, blue, and white marls, and shales, with gypsum 
and beds of rock-salt. (Marnes irisées of the French.) 
2. Variegated red and white sandstones. 
3. Conglomerates formed of the detritus of the older rocks. 
4. Red mottled sandstone, and marls. (Grés-bigarré of the French.) 
* See “ Petrifactions,” p. 337—367. 
tT Called by some geologists Potkilitic (variegated) group. 
& 
