178 Great Oolite. 



going south along the Oolites, the Stonesfield Slate 

 rapidly thins away, or changes itslithological character, 

 for it is quite unknown at the base of the Great Oolite 

 towards Wotton-under-Edge and Bath. In the opposite 

 direction going northward, the Stonesfield Slate passes 

 into the Northampton Sand, where we will leave it for 

 the present. 



The Great Oolite was originally so called -by William 

 Smith in 1812, and the Upper Oolite in 1815, to dis- 

 tinguish it from the Lower or Inferior Oolite, which lies 

 below the Fuller's Earth, whereas the former lies above 

 it. It is often named the Bath Oolite, and the greatest 

 development of that excellent building-stone is near 

 the city, which is almost entirely built of ' Bath stone.' 

 It first makes its appearance on the south near Norton 

 St. Philip, about six miles south of Bath, from whence, 

 overlaid by Forest Marble, it ranges northerly, forming 

 the flat-topped scarped hills on either side of the Avon 

 near Bath, and so on by Wotton-under-edge to Minchin- 

 Hampton. Beyond this it forms a large part of the 

 table land, intersected by valleys, that lie between 

 Minchin-Hampton in Gloucestershire and Towcester in 

 Northamptonshire. In Northamptonshire its lowest 

 sandy beds are the equivalents of the Stonesfield Slate, 

 To this part of the subject I shall return in describing 

 important physical changes that take place further 

 north. 



The best beds of the Great Oolite are of cream- 

 coloured limestone, so soft when first extracted from the 

 quarry, that it can be easily sawed into blocks, but 

 hardening on exposure. Some of its fossils are also 

 found in the Fuller's Earth and the Inferior Oolite, and 

 a few are first known in the Lias, and, indeed, through- 

 out the whole there is a general agreement in the 



