176 Fullers Earth. 



Plants are rare in the purely marine strata of 

 Gloucester shire and the south of England, but frag- 

 ments of coniferous trees are sometimes found, the 

 most remarkable of which is a large cone of Araucarites 

 hemisphcericus. This, in addition to the nature and 

 multiplicity of genera and species of the marine fauna, 

 plainly tells of land not far off, a fact that will become 

 still more clear as we get further on with the history 

 of the Oolites, and its bearing on the old physical 

 geography of the land of the Oolitic epoch. 



THE FULLER'S EARTH accompanies and overlies the 

 Inferior Oolite through the whole length of this area, 

 excepting where locally interrupted by faults. It con- 

 sists chiefly of tenacious bluish clay, with frequent thin 

 shelly bands of limestone, often largely charged with a 

 small oyster, Ostrea acuminata, and with Terebratulae. 

 In the neighbourhood and south of Bath a strong band of 

 limestone lies in the middle of the clay, known as the 

 Fuller's Earth Kock. 



Near Upper Slaughter in Oxfordshire, this sub- 

 formation entirely thins away, and is known no more. 

 Its greatest thickness, near Bath, is about 200 feet. 

 The name was originally given to it by William Smith, 

 because in places it contains beds of Fuller's Earth, long 

 ago much used in the famous woollen factories of 

 Gloucestershire. I call it a subformation, because 

 very many of its fossils are also common in the Inferior 

 Oolite, though a few are peculiar. 



THE GREAT or BATH OOLITE of this southern half 

 of England succeeds the Fuller's Earth, and consists, 

 when fully developed, of 



Forest Marble. 

 Great Oolite. 

 Stonesfield Slate. 



