70 OOLITE. 



may of course be yet discovered in many other parts of the 

 world. 



The series, as shown in the neighbourhood of Bath, is (be- 

 ginning with the lowest) as follows : 1. Lias, a set of strata 

 variously composed of limestone, clay, marl, and shale, clay 

 being predominant ; 2. Lower oolitic formation, including, 

 besides the great oolitic bed of central England, Fullers'-earth 

 beds, Forest marble, and Cornbrash ; 3. Middle oolitic for- 

 mation, composed of two sub-groups, the Oxford Clay and 

 Coral Rag, the latter being a mere layer of the works of the 

 coral polype ; 4. Upper oolitic formation, including what are 

 called Kimmeridge clay and Portland oolite. In Yorkshire 

 there is an additional group above the lias, and in Sutherland- 

 shire there is another group above that again. In the wealds 

 (moorlands) of Kent and Sussex, there is, in like manner, 

 above the fourth of the Bath series, another additional group, 

 to which the name of the Wealden has been given, from its 

 topographical situation, and which, composed of sandstones 

 and clays, is subdivided into Purbeck beds, Hastings sand, and 

 Weald clay. 



There are no particular appearances of disturbance between 

 the close of the Trias and the beginning of the Lias and Oolite 

 system, as far as has been observed in England. Yet there is 

 a great change in the materials of the rocks of the two forma- 

 tions, showing that, while the bottoms of the seas of the one 

 period had been chiefly arenaceous, those of the other were 

 chiefly clayey and limy. And there is an equal difference 

 between the two periods in respect of both botany and zoology. 

 While the Permian and Triassic systems, with the single ex- 

 ception of the Muschelkalk, show comparatively scanty traces 

 of life, those in the lias and oolite are extremely abundant, 

 particularly in the department of animals, and more particu- 

 larly still of sea mollusca. The distinguishing characters of 

 the zoology appear to be uniform over a great space. " In 

 the equivalent deposits in the Himalayan Mountains, at Fer- 

 nando Po, in the region north of the Cape of Good Hope, and 

 in the Run of Cutch, and other parts of Hindostan, fossils 

 have been discovered, which, as far as English naturalists who 

 have seen them can determine, are undistinguishable from cer- 

 tain oolite and lias fossils of Europe." 1 



The dry land of this age presented cycadece, " a beautiful 

 class of plants between the conifers and palms, having a tall, 



1 Murchison's Silurian System. 



