1 66 



CHAPTER XII. 



LIASSIC AND OOLITIC, OR JUKASSIC STRATA. 



IN the previous chapter, I stated that the continental 

 area in which lay the lakes of the epoch of the New Red 

 Marl, underwent partial submersion, during which our 

 passage beds, called the Rhsetic or Avicula contorta 



Jr o 



strata, were deposited. This sinking of the land going 

 on by degrees, resulted in the formation of groups of 

 islands, round which, first the LIAS, and afterwards the 

 OOLITIC SERIES were deposited, the whole, on the Con- 

 tinent of Europe, and now often in Britain, being 

 grouped under the name of Jurassic formations. 



The general stratigraphical relations of the larger 

 masses of the Liassic and Oolitic series, in the southern 

 half of England, will be easily understood by reference 

 to fig. 5, p. 25. 



The high ground now called Wales and Hereford- 

 shire, undoubtedly formed part of one of these islands ; 

 Dartmoor and other palaeozoic elevations in Devon and 

 Cornwall formed others ; probably the hilly regions of 

 Derbyshire another ; and, certainly, the Cumbrian 

 mountains a fourth ; while there can be no doubt that 

 parts of the south of Scotland, and the greater heights 

 of the Highlands, also stood as islands washed by the 

 Liassic sea. 



It is not, however, to be supposed that the actual 



