Horace B. Woodward — On the Metamorphism of Strata. 401 



absence of any clear section this estimate is merely approximate. 

 The molluscan remains, of which the species collected by the 

 Geological Survey were determined by Mr. Etheridge, show that 

 the Ehastic and Lower Lias formations are here represented.^ The 

 fossils are changed like the rock in wliich they are imbedded ; 

 occasionally the shells have been dissolved away, leaving cavities. 

 Associated with the Dolomitic Conglomerate there often occur in 

 the same vicinity cherty beds somewhat similar in character to the 

 above-mentioned deposits ; they may be seen by the road- side at 

 Eastwood House, near East Harptree, and on the hill above this 

 spot, and near Green Down Cottage. 



Previous Observers. — These deposits have attracted much notice ; 

 but, from the earlier observers having confounded the two, some con- 

 fusion at first arose. Thus Mr. Weaver^ referred them both to the 

 Greensand ; the Eev. W. D. Conybeare,^ pointing out the fossil 

 remains found in the cherty beds at one place, and the association of 

 chert with the Magnesian (Dolomitic) Conglomerate at another, 

 referred the whole, though with hesitation, to the Magnesian Lime- 

 stone. Later he and Dr. Buckland* placed them with the Dolomitic 

 Conglomerate. In the Geological Survey Maj), Sheet 19, the fossil- 

 iferous beds were included with the Lower Lias, those of Keuper 

 age were mapped with the Dolomitic Conglomerate, or with the 

 New Eed Marl.'' 



Details of Liassic Beds. — The surface of the ground at Harptree 

 Hill is covered with hollows, some sunk to obtain ochre from thin 

 clayey beds interstratified with the chert, others to obtain calamine 

 from the Dolomitic Conglomerate beneath the chert, while, again, a 

 few are undoubtedly natural hollows or pot-holes due to dissolution 

 of the Mountain Limestone where it underlies the chert. These pits, 

 being generally covered with a loose talus, rarely afford any section 

 of the beds. The best exposure is seen in a pot-hole, about 60 feet 

 in diameter, east of the road, and about half-way between East 

 Harptree and the " Castle of Comfort." The beds shown, to a depth 

 of nearly 20 feet, consist almost entirely of massive chert, in layers, 

 from one to three feet in thickness, separated by thin clayey partings 

 (probably of subsequent subaerial formation), and standing out 

 sharply, but sometimes weathering sandy (at the exterior). Lower 

 Lias fossils occur in the top beds, while very probably the lower 

 beds represent the White Lias, but in these no fossils were detected. 

 In places, indeed, some beds have a curious resemblance to the Sun- 

 bed, or top limestone of the White Lias in Somersetshire, which 

 usually has a flinty appearance and conchoidal fracture. Beneath 



^ Mr. Sanders, F.E.S., has collected a series of fossils from these beds, -which he 

 has placed in the Museum at Bristol. They have also been briefly alluded to by Mr. 

 C. Moore, Quart. Journ. Geol. Soc, Tol. xxiii., p. 492, and Mr. E. B. Tawiiey, ibid, 

 vol. xxii., p. 79. Lists -will be published in the official explanation -which -will ac- 

 company the ne-w edition of Sheet 19 of the Geological Survey Map. 



2 Trans. Geol. Society, second series, vol. i. p. 364. 



3 Geology of England and Wales, p. 304. 



* Trans. Geol. Society, second series, vol. i. p. 294. 



* The former -were alluded to by De la Beche, Mem. Geol. Survey, vol. i. p. 277. 



VOL. viir. — NO. Lxxxvii. 26 



