h 6 



Dr. FiTTON on the Strata below the Chalk. 281 



Ft. In. 



T. Under the ochre are irregular flattened ovoid masses, about 18 inches thick, consisting ■ 

 of stratified matter which contains shells. These masses were divided thus: — 

 a. Thinly stratified, greenish grey, Fuller's earth, decomposed. The lowest part 

 sometimes including thin seams of coaly matter, the remains, apparently, of 

 highly compressed stems of plants; with fragments of shells. 

 6. Tiiinly stratified, dark grey, alternating with lighter-coloured, sandy clay. Like 

 the alternation which is frequent at the bottom of the lower green-sand, and in 

 the Wealden, described above at p. 1G8. (83.) 



8. Greenish matter, often stratified ; — coarse Fuller's earth 3 



[Portland stone :] — 



9. Whitish rubbly stone, not unlike freshwater limestone, but containing Perna quadrata,\ , 



with ribbed and tuberculated Trigoniae 1 3 to j 



10. " Pitcliing-stone*'\ consisting of — 



a. Hard compact grit : sand concreted by a very large proportion of cal- 

 careous matter about 9 



6. Fuller's earth, yellowish-green 6 in. to 8 



c. Compact grit ; — more siliceous than a 7 ^ 



1 1 . Grey clay, in about three layers 6 



12. Limestone in two beds, including Pernae about 2 6 



13. " White limestone" ; as below. Pecteii orbicularis abundant 3 ft. to 4 



D. — At a pit on the south-west brow of Brill Hill, (a continuation downwards of beds above 

 enumerated), the following is the order : — 



(13.) " White limestone" (like the "Chalk" of Chicksgrove, 7. p. 253.) used only for making-i 



lime'; sometimes harder and bluish. It occurs in irregular masses, and has the aspect of I 3 

 freshwater stone, but contains numerous Trigonice about J 



14. " Cap of the Greys". Brownish clay, full of fragments of shells "j 



15. " Greys". Good stone for building, full of Pernae. Some of the beds contain stems, j-^ "' 

 like those of Siphoniae J 



Below the " Greys" are about 9 feet of alternate courses of indifferent stone and of 

 yellowish grey sand, with Portland fossils — Cardium dissiniile, Pecten lamellosus, 

 Trigonta gihbosa. These are succeeded by sand charged with green particles, which, 

 in the following list, is referred to the Portland sand ; in which Ammonites giganteus 

 is frequent, in some specimens with Oysters attached. 



In some places here also, are erosions or cavities in the upper part of the stony strata, like 

 the •' Gulls " of Great Hazeley, (p. 27G). 



Portland Sand. — -Good sections of this group are to be found in all directions around the 

 village of Brill; in the descent of the hill from Long Crendon towards Thame; and on the north- 

 east of the latter village. 



Sections at Long Crendon, and thence on the Descent towards Thame. 



One of the principal quarries at the upper part of the hill at Long Crendon exhibited the fol- 

 lowing beds : — • 



Tough loamy clay about 2 



* I have, in these lists, inserted the names in use among the quarrymen, as they may assist 

 in identifying tlie strata in other parts of the country; the same pits seldom remaining open more 

 than a few months. 



2 o 2 



