§25. THE LIAS. 



523 



The edges of these basins consist of strata thrown 

 up at a high angle, and often nearly vertical, forming 

 bold and precipitous ranges of hills ; in the valleys, hori- 

 zontal layers of lias, with subjacent beds of red marl, are 

 seen lying unconforraably upon the highly inclined coal 

 measures (IAgn. 118, 3, 3, 3). I shall recur to this 

 subject hereafter, and now only observe, that the Lias 

 appears beneath the Oolite through the south-east of 

 Somersetshire, and passes into Dorsetshire, where the over- 

 lying Green sand conceals it beneath the high range of the 

 Black Down hills. 



At Lyme Regis it forms a range of cliffs, about four miles 

 in length, and may be traced till it gradually sinks beneath 

 the Inferior Oolite. The skeletons of large marine reptiles 

 {Ichthyosauri and Plesiosauri\ for which the Lias is cele- 

 brated, have principally been found in the cliffs at Lyme, 

 Watchett, Westbury, and Whitby, where the natural sec- 

 tions, formed by the action of the waves, well display the 

 characters of the strata, and afford abundance of fossil re- 

 mains. The Lias appears in the Western Isles of Scotland, 

 and on the north-east coast of Ireland. 



In the north and south-east of France, and over a large 

 area in Germany, the Lias, with its peculiar fossils, accom- 

 panies the Oolite. One species of Gryphite (Gryphea 

 mcurva, Lign. Ill, Jig. 6) which is so abundant in the 

 Liassic strata of England, on the Continent forms a lime- 

 stone (Calcaire a gryjrfiites), which, like the Sussex marble, 

 is composed of shells cemented together by a calcareous 

 paste. In Wirtemberg the Lias presents the usual charac- 

 ters of that of England, and contains remains of Ichthyo- 

 sauri and other saurians.* 



In the valley of the Arve, in Switzerland, the Lias clays 

 are of great thickness ; and owing to the ancient effects of 



* See Dr. Jaeger's work, Uber die Fossile Eeptilien welche in Wur- 

 temberg aufgefunden worden sind. Stutgard, 1828. 



