348 JURASSIC. 



uptilted. The beds may also have been subject to atmospheric 

 influences during Purbeck times.' 



The Purbeck Beds of the Vale of Wardour are well exposed in 

 the railway-cutting west of Dinton Station and in quarries near 

 TefFont Evias, Wockley, and Chilmark. The Rev. W. R. Andrews, 

 who has paid much attention to the beds, remarks that they are 

 only 60 or 70 feet in thickness, and belong to the Lower and 

 Middle divisions. They rest conformably on the Portland series, 

 and are overlaid by Wealden strata. " Whether the Upper 

 Purbecks were ever deposited here it is impossible to say," but 

 Mr. Andrews is of opinion that the Wealden Beds were laid down 

 on an eroded surface of the Purbeck Beds.^ The beds are as 

 follows : — 



Wealden. — Yellow and red sandy clays. Endogoiiies erosa. 



!Hard marls, clays and limestones. Archa:o7iisais Brodiei. 

 Cinder Bed with Ostrea distorta, Trigonia densinoda and T. 

 gibbosa. 

 Hard limestones and sandy rock. 



p , , > Clay, marl. (Insect -beds, etc.) 



So abundant are remains of Archceoniscus, that 250 specimens 

 have been obtained on a slab not larger than one foot square. 



Traces of Purbeck Beds occur at Brill in Buckinghamshire ; 

 consisting chiefly of argillaceous beds having a thickness of 10 feet.^ 

 Purbeck Beds, with a thickness of 4 feet, occur at Shotover Hill. 

 The term Pendle is applied to fissile argillaceous limestones that 

 occur near the base of the Purbeck Beds at Hartwell and other 

 localities in the neighbourhood ; they yield Fish-remains, Insects, 

 Cyprides, Ferns, etc. 



Near Swindon the Purbeck Beds are represented by hard cream- 

 coloured marly limestones and clays (with Paliidina, Bithynia, etc.), 

 about 12 feet thick. Here Mr. C. Moore obtained remains of 

 Mammals, and also of the oldest known Frog.'* 



In Sussex the Purbeck Beds occur near Battle, where they were 

 formerly classed with the Ashburnham (Wealden) Beds. The total 

 thickness of these Purbeck Beds is stated by Mr. Topley to be 

 about 400 feet. The Sub-Wealden boring passed through 180 feet 

 of this formation, consisting of limestone, shale and marl, with beds 

 of gypsum. The higher beds consist chiefly of shales, with two 

 groups of limestones, the upper termed the ' Greys,' and the lower 

 the ' Blues.' Cyrcna and other Mollusca, and Cypridea Valdensis 

 occur sometimes abundantly in the shales. Paludina is rare, and 

 Ostrea has only occasionally been met with.^ 



1 See also Rev. O. Fisher, Trans. Cambr. Phil. Soc. ix. 



2 Q.J. xxxvii. 251 ; see also Rev. O. Fisher, Q. J. x. 476 ; J. F. Blake, Q.J. 

 xxxvi. 200 ; Brodie, Foss. Insects, p. 3. 



2 Rev. P. B. Brodie, Q. J. xxiii. 197; see PhiUips, Geol. Oxford, p. 415 ; 

 J. F. Blake, Q. J. xxxvi. 215. 



* Proc. Geol. Assoc, iv. 544. 



5 W. Topley, Geol. Weald, pp. 16, 30, 408. A full account of the literature 

 is there given. 



