34 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [Apr. 6, 



D. Sections of the Inferior Oolite in Somersetshire and Dorset. — In 

 some parts of Somersetshire the beds under consideration are more 

 or less developed. 



1. Glastonbury Tor. — A solitary outlier of the Upper Lias 

 Sands is seen at Glastonbury Tor. This remarkable cone is about 

 500 feet high (aneroidal measurement*), and presents the folio wing- 

 Section : — 



feet. 

 Brown and yellow sands, incoherent where exposed .... 190 

 Light-coloured "Upper Lias ragstones, containing Ammo- 

 nites bifrons, A. Holandrei, A. radians, A.falcifer, A. 



communis, and A. crassus 14 



Marlstone-rock, with Ammonites margaritatus, about .... 15 

 Marlstone- sands, well exposed where cut through by the 



road 30 



Middle Lias (concealed) 1 , n -, ocn 



T T . > t -,< y probably 250 



Lower Lias (concealed) J l J 



2. Yeovil. — Around Yeovil the Upper Lias Sands are equally 

 well developed, and admirably exposed in numerous sections in the 

 roads, lanes, and railway-cuttings, where they vary in thickness : 

 at the Half-way House the sands were bored, in sinking a well, to 

 a depth of 140 feet before reaching the Lias Clay ; near Yeovil they 

 are traversed by layers of large nodules at varying intervals of from 

 4 to 6 feet. These nodules rarely contain fossils, but are so much 

 indurated that they are used as building- stone in the Central Somer- 

 set Railway. At Down Cliff, on the coast of Dorset, similar nodules 

 form a micaceous sandstone, on the surface of which Ophioderma 

 Egertoni, Brod., only is found. 



The Inferior Oolite, which near Yeovil immediately overlies the 

 sands, is comparatively thin, in consequence of the absence of the 

 thick-bedded limestones which impart such a thickness to this forma- 

 tion in Gloucestershire. It consists of the middle and upper divi- 

 sions of that formation. The bottom-bed is an extremely hard, 

 crystalline, greyish- coloured limestone, called the " Dew-bed," 

 which is raised for road-material, and contains a few shells and 

 Polyzoa, some bones and fossil wood. This is overlain by a shelly, 

 iron-shot, oolitic limestone, extremely rich in fossil shells, and from 

 which nearly all the Gasteropoda and Conchifera contained in my 

 list were obtained. This is succeeded by an Ammonite-bed, con- 

 taining many fine specimens of Ammonites Sowerbyi, A. BraiJcenridgii , 

 A. concavus and A. Dorsetensis. Above the Cephalopoda, come in 

 lighter-coloured, thin-bedded, oolitic limestones, with Ammonites 

 ParTcinsoni, A. Truellei and A. Martinsii, which are overlain by 

 bands of oolitic freestone, interstratified with light-coloured marls. 

 Such is the general character of the three sections which I have 

 examined, and of which I subjoin detailed descriptions. 



tained from a similar ferruginous rock at Grlazedale. It appears to represent 

 that bed, both lithologically and palseontologically. 



* My friend E. H. Day, Esq., of Weston-super-Mare, obtained these measure- 

 ments by his aneroid barometer. 



