OOLITIC. 



281 



OOLITIC. 



Fig. 45. — KiMERiDGE Bay, looking Westwards towards Gad Cliff 

 (Portland Rocks) and Lulworth. 



The term Oolite, introduced by Wm. Smith, indicates the charac- 

 teristic features of most of the limestones in the series, which have 

 an oolitic structure ; but it must be borne in mind that this 

 structure is occasionally present in rocks of all ages. Oolite or 

 roe-stone (derived from the Greek oon, an ^^g, and lithos, stone) 

 is a name applied to limestones composed of small round particles 

 of calcareous matter, which are cemented together and resemble 

 the roe of a fish. When these particles approach the size of a pea 

 or bean, the rock is termed Pisolite, Pisolitic limestone, or Pea-grit. 

 Thus we have the Inferior Oolite, the Great or Bath Oolite, the 

 Coralline or Oxford Oolite, and the Portland Oolite ; also the Pea- 

 grit, a local member of the Inferior Oolite. 



The organic remains of the Oolitic period include the Reptiles 

 Megalosaiirus and Ceteosaurus, besides Teleosaurus, Ptavdactyhis and 

 other forms known in the Lias. The period was termed the Megalo- 

 saurian by John Phillips. Among Mammalia, there were many 

 genera of Marsupials ; and these, together with MoUusca such as 

 Trigonia, some species of Terebratiila, and other forms of life, present 

 many striking resemblances to the modern fauna and flora of 

 Australia. The Mammals were mostly of diminutive size, and 

 referring to them Sir R. Owen has remarked that the results of 

 palaeontology sometimes move one to exclaim, in regard to Tertiary 



