54 Rev. P. B. Brodie on the Geology of the 



account much better adapted for ceconomical purposes. Two 

 genera of plants only are mentioned by Mr. Morris, Pecopteris 

 and Zamites, and these in patches and fragmentary, scattered 

 through certain portions of the beds overlying the slate. But 

 these must be limited to particular spots, for in the four quarries 

 I visited on Colly weston Hill I saw scarcely a trace of any, and 

 I was struck by their apparent rarity in that district, compared 

 with their abundance in certain divisions of the slate at Seven- 

 hampton and other localities near Cheltenham. The absence of 

 the varied flora so characteristic of the slate near Cheltenham 

 and Oxford, is not more remarkable than is that of the other in- 

 teresting terrestrial and marine remains which it there contains. 

 I saw no teeth or bones of reptiles and fish, nor elytra of beetles, 

 nor could I learn that the workmen had ever observed any ; and 

 hence zoologically the Collyweston slate differs more from its 

 south-western equivalents than it does in its internal mineralo- 

 gical structure. These facts lead to the inference that it was de- 

 posited beneath a deeper sea, and at a greater distance from land, 

 whence we should expect to find few evidences of neighbouring 

 coasts, and a larger assemblage of marine exuvise, the denizens 

 of deeper water, though the genera would not be very numerous. 



On the whole, the Great Oolite and its associated beds in their 

 extension northwards, bear a closer resemblance to the Yorkshire 

 than to the Bath and Minchinhampton series, except a portion 

 of the upper beds at Ketton and Casterton. 



For further details I may refer to the " Notice of the Geology 

 of the neighbourhood of Stamford and Peterborough," by Cap- 

 tain Ibbetson and Mr. Morris, published in the Transactions of 

 the Meeting for the Advancement of Science, 1847. When I 

 visited Lincolnshire I had not seen this interesting paper, and it 

 appears that we had independently arrived at the same conclusions. 



Great Oolite (continued) North of Grantham. 



There are some large and valuable quarries of Great Oolite at 



Aucaster, eight miles north-east of Grantham, which have long 



been famous for their beautiful building- stone. The following 



section will explain its general character in descending order : — 



1 . Blue clay, in which I could detect no fossils ; perhaps the repre- ft. in. 



sentative of the Bradford clay, which in Wilts immediately 

 overlies the Great Oolite, and often separates the minor 

 subdivisions. Near the top it is traversed by a thin diugy- 

 white kind of marl, with a few imperfect impressions of plants 12 



2. Ragstone — coarse, shelly, hard oolite 5 



3. Sandy, soft (rarely shelly) oolitic freestone, variously coloured, 



yellow, pink and white, which often gives it, from its variegated 

 wavy hues, a beautiful appearance. This forms the famous 

 building-stone, and yields very large blocks 17 6* 



4. Hard, shelly oolite, generally of a blue colour. Not worked . . 16 



5. Soft white stone below, depth uncertain. 



Total 50 6 



