302 JURASSIC. 



Algae, Ferns, Cycads, and Conifers ; among the genera are 

 Ptcrophylhim, Pccoptcn's, TcEuiopteris, TImytcs, Ai-aucarifcs Brodici, etc. 



According to Prof. Phillips, the beds were probably laid down 

 in a lagoon with bordering marshes and drier land, while the 

 organic remains present remarkable affinities with forms now living 

 in Australia.^ 



The flaggy beds are quarried in the Evenlode Valley, at Sarsden, 

 Stonesfield, and Woodstock, also on Sevenhampton Common, Eye- 

 ford, near Naunton, Bisley, etc.^ 



The deposit worked for ' slates ' is sometimes only a foot in thickness, but it 

 generally consists of two fissile beds of a buff-coloured or grey oolitic limestone 

 called pcndlc, each about two feet thick, separated by a bed of loose calcareo- 

 siliceous sandstone called race, about the same thickness. Concretions are 

 frequent in the latter, and are called whinstoties or pot-lids ; they are partially 

 oolitic, and vary from six inches to two feet in diameter ; their form is generally 

 that of a flattened sphere ; they break into parallel planes, and often contain shells. 

 The pendle, after being quarried, is suffered to lie exposed to the action of a 

 winter's frosts, and the blocks being then struck on their edge with a mallet, freely 

 separate into slates sufficiently thin to afford a light material for roofing. The 

 quarries are principally situated immediately to the south of Stonesfield village, 

 in the valley which branches off eastwards from that of the Evenlode. The mode 

 of working is by driving horizontal galleries about six feet high into the side of the 

 hill, and then extracting the two strata of pendle laterally, piling up the refuse 

 masses of the intermediate bed of race, so as to support the roof: deep 

 perpendicular shafts communicate with these galleries. These workings have 

 been carried on from remote times to a considerable extent, so that both sides of 

 the valley are completely honey-combed by them. Beautiful plumose stalactites 

 are often found in the fissures of the rock, and are called tallo-u by the workmen.' 



FOREST MAEBLE. 



This formation was named by William Smith in 1815, from the 

 Forest of Wychwood, between Burford and Woodstock, in Oxford- 

 shire. It comprises thick beds of clay and shale, also sand, 

 sandstone, and oolite, but its characteristic rock is a fissile* shelly 

 and oolitic limestone, which has been polished in some localities 

 for ornamental purposes. Few formations are more changeable in 

 character within short distances ; and the stone-beds are conspicu- 

 ously false-bedded and wedge-bedded. These beds are usually 

 overlaid and underlaid by shaly and marly clays, that contain thin 

 layers or films of calcareous sandstone. 



The thickness of the Forest ]\Iarble in north Dorsetshire has 

 been estimated at 450 feet by IMr. Bristow, but it diminishes north- 

 wards, being about 100 feet near Bath and Cirencester. The main 

 mass of the stone-beds is seldom more than thirty feet in thickness, 

 but occasional beds of shelly limestone are found at all horizons in 



1 G. Mag. 1866, p. 99 ; Geol. Oxford, etc., pp. 16S, 237 ; Owen, Brit. Fossil 

 Mammalia; Brodie, Fossil Insects ; Brodie and Buckman, Q.J. i. 220. 



2 Hull, Geol. Cheltenham (Geol. Survey), p. 53 ; Hull, Explan. Sheet 45 S.W. 

 p. 18 ; and A. H. Green, Geol. Banbury, etc. (Geol. Survey), p. 13. 



2 Conybeare and Phillips, Outlines of the Geol. England and Wales, p. 204. 

 * A term applied to beds capable of being split up into flags. 



