214 KEY. J. P. JJLAKE ON THE 



below by an accumulation of shells, so that at the base it is full of 

 Trigonia gibbosa and other fossils. This varies in thickness in the 

 quarries from 5 feet to 8 feet, but is always the object of the exca- 

 vations. It is separated from the overlying rocks by a thin band 

 of clay, still full of broken Trigonice, which, in an ill-preserved 

 state, abound throughout all the sections where any fossils occur at 

 all, and especially towards the base. The next bed (2) is similar to 

 the one below, but has the appearance of rolled masses of stone, so 

 consolidated by similar material, that the separate pieces are scarcely 

 recognizable, the whole being from 4 feet to 5 feet thick. The top (1) 

 is a solid block of gritty limestone, 2 feet thick, with Pernce, The 

 chief fossils lie here in beds ISTos. 2 and 3. The upper one contains, 

 among others, CeritJiium portlandicum ; and the lower one has Tri- 

 gonia incurva, Lima rustica, Pecten la7nellosus, Ostrea eocpansa, 

 and Pleuromya tellina. The presence of the last two is worthy of 

 note. A similar section may be seen at Cuddesdon, where the road- 

 way of the village is for some space made by No. 2. But it is dif- 

 ficult to find in this district any exposure of the lower beds. Pits 

 are opened and closed again so rapidly that it is a chance at any 

 moment whether any are visible. There is a road-section to the 

 west of Great Milton, which might well commence at the base of 

 No. 4 ; but its indications are not very satisfactory. It would show 

 that there is a rubbly limestone (5) with Pleuromya and Cardium 

 (? dissimile), which is very argillaceous towards the centre, and is 

 followed below by nodular sand (6). The thicknesses, which are 

 not great, cannot be accurately ascertained. Glimpses may be 

 caught of a similar succession at Cuddesdon and Garsington. At 

 the former, dark rubbly beds with green grains and small pebbles 

 form the upper boundary of a pond, so that they are probably pre- 

 ceded by clay ; and at the latter a temporary excavation showed 

 4 feet of rubbly green glauconitic beds full of fossils, in which Car- 

 diwn Pellati, Trigonia incurva ?, and Ammonites bipleoc abounded, 

 but Tingonia gibbosa was very rare. This became very soft and green 

 towards the base, with a number of small stones. Wot more than 

 30 feet intervene between this and the Kimmeridge Clay, which, all 

 over this district, is of the same sandy character at the top as it is 

 at Swindon. 



We are now able to place in its proper position the well-known 

 section at Shotover given by Pitton*, Phillips t, and SsemannJ. 

 This gives, as the latter author has shown, a bank with fossils, in- 

 cluding Trigonia gibbosa at the top, and doubtless the home of many 

 of the fossils quoted by Phillips. This corresponds to No. 5, and is 

 succeeded downwards by non-glaucouitic non-fossiliferous sands, and 

 then sands which are both glauconitic and fossiliferous and contain 

 the huge doggers, as at Swindon. The total thickness seen here is 

 estimated by Prof. Phillips at from 70 to 80 feet. There can be no 

 mistaking these sands, with their glauconitic grains and fossils such 



* Log. cit. p. 278. t Geology of Oxford, p. 413 and pi. 16. 



\ De Loriol and Pellat, Mem, Ac. Soc. Phys. et Hist. Nat. Greneye, torn. six. 

 p. 192, pi. i. 



