160 



with Chlorite: see the under figure ; and Woodward men- 

 tions greenish sand from Woolwich, p. 11. Lord Alta- 

 mont, Dr. Clarke and Mr. Warburton have since favoured 

 me with some sandy Lime from the Castle Hill, near 

 Cambridge, where it is very abundant, and contains nu- 

 merous petrifactions. 



TAB. CLXXXIV. 



1 his forms an appearance not unlike Mortar with the 

 green Chlorite among it. When it has a more perfect ap- 

 pearance of mortar without the green, it is considered as 

 good manure, and is provincially called Goult. It is often 

 found about a foot from the surface. This is chiefly used to 

 make the best white bricks of Cambridgeshire. That with 

 granular Talc or Chlorite is of a dull hue, and is found 

 deeper. The same substance, somewhat more compact, 

 is called in Ireland Mulatto-Stone : see tab. 185. I have 

 figured some of the petrifactions that occur, considering 

 them as useful to mineralogy. Those in this stone are 

 generally of a dark brown stony appearance, accompanied 

 bv rugose lumps of various sizes of nearly the same sub- 

 stance, somewhat similar to the swampy Iron Ore of 

 Kirwan, v. 2. 183. The petrifactions are coloured like it, 

 sometimes with a nearer approach to the hue of Pyrites. 

 These petrifactions are the round one on the left handy 

 supposed a hinder tooth of some fish ; the right hand is 

 considered as a fish's bony palate; the middle upper figure 

 is a bivalve shell, the upper valve remaining in the state of 

 Carbonate of Lime, the lower one browned with the ore. It 

 is a kind of Anomia called a Gryphite, very frequent among 



