328 THE PORTLAND OOLITE PERIOD. CHAP. 



5. Calcareous sand, passing up into limestone, 5 feet, containing a bed about I foot 



thick, almost entirely composed of Terebra Portlandica. 



3. Clay containing a bed of Oatrea falcata and Perna quadrata (mytilloides) , I to 



2 feet, 



4. Sand and sandstones, 25 feet ; the lowest portion most fossiliferous. Cardium 



dissimile. 

 a. Pale blue stratified sandstone, 5 feet. 



1. Thin seam of black sub-angular pebbles, of which a portion is always to be seen 



attached to the lowest masses of sandstone. 



The same author gives a section of the detached deposit of 

 Portland beds as observed at Bourton, a few miles east of Swindon : 



9. Stratified earthy oolite with Ammonites, and casts of Trigonise in 



abundance 8 feet. 



8. Buff-coloured sands, with bands of pale yellow sand. No fossils . 12 



7. Flat-bedded white oolitic sand. No fossils 8 



6. Rubbly oolite. Large Pleurotomarice . . . . . . i ,, 



5. Thick-bedded fossiliferous band . ', . . . 3 



4. Ostrea and Perna bed .',. ... . . . . . 



3. Pebbles in calcareous beds. Fossils numerous . . . . .10,, 



2. Fine sands . . . . . . . . . 7 



i. Kimmeridge clay -=r--, >. . . ,, 



At Great Ilazeley the stone found between thick uniform grey 

 sands, and iron sands and white clays like those of Shotover, is of 

 good quality, and worked to a considerable extent for ashler, slabs, 

 tombstones, and walling ; being a fine sandy oolite, with layers of 

 the ordinary shells, viz. trigoniae, pectines, ostrese, &c. It is ob- 

 tained at some considerable disadvantage from under the thick 

 cover of ferruginous sands. 



At Brill the Portland rock is thin and lumpy, but white and 

 very fossiliferous. It is extracted with difficulty from under a mass 

 of laminated Purbeck clays and limestone, these being covered by 

 thicker layers of sands and clays of the iron-sand series. Much 

 the same characters accompany the rock at Quainton and other 

 localities on the hills north of Aylesbury, beyond which it cannot 

 be traced further to the east. 



FOSSILS OF THE PORTLAND OOLITE AND KIMMEKIDGE CLAY. 



Abbreviations : K. C. for Kimmeridge Clay ; P. S. Portland Sands ; P. R. Portland 



Rock. 1., m., u. lower, middle, and upper. 

 PLANTS. Fragments of wood in each of the divisions. 

 ACTINOZOA. None have been collected in the Oxford district. 



