Vol. 59.] THE TOA-RCIAN OP BEEDON HILL. 445 



36. The Toaecian o/Bkedon Hill, 1 and a Compaeison with Deposits 



elsewhere. By S. S. Buckman, Esq., F.G.S. (Eead May 27th, 



1903.) 



Contents. 



Page 



I. Geology 445 



II. Comparison with the Cotteswolds 448 



III. Comparison of the Cotteswolds and Dorset 451 



IV. Comparison with Normandy 452 



V. Ghronometry of the Toarcian 455 



VI. Retrospect 456 



VII. Comparison of Terms 457 



VIII. Summary , 458 



I. Geology. 



The Upper Lias (G 3) of Bredon Hill is shown on the Geological- 

 Survey map as more than 300 feet in thickness. It is said to be as 

 much as 380 feet thick, whereas at Wotton-under-Edge, some 36 miles 

 to the south, it is said to be only 10 feet. 2 But at the former locality 

 the Inferior Oolite (G 5) is represented as resting directly on the 

 Upper Lias (G 3) ; at the latter locality there is shown, between 

 Inferior Oolite and Upper Lias, a development of some 150 feet of 

 strata called ' Midford Sand' (G4) — the Cotteswold Sands overlain 

 by the Cephalopod-Bed. The question often presented itself to my 

 mind — Were the two so-called ' series' of Upper Lias the same, or 

 was not the Upper Lias of Bredon Hill really much more than the 

 Upper Lias of Wotton, so that there was not a true comparison? 

 W as it not an argillaceous condition of the sands and the overlying 

 Cephalopod-Bed ? 



Some few years ago I was able to answer this question partly in the 

 affirmative. On the north slope of Bredon Hill, I found in some 

 argillaceous stones in a gateway, many feet below the yellow 

 limestone of the Inferior Oolite, portions of ammonites indicative 

 of beds contemporaneous with the Cephalopod-Bed of the Cottes- 

 wolds : they indicated strata of the hemerse Moorei, dispansi, 

 and Struckmanni. 



When the Cotteswold Naturalists' Field-Club visited Overbury on 

 the south side of Bredon Hill, in 1902, the members found in the 

 gravel-pit many ammonites confirming my discovery. At a subse- 

 quent visit, which I paid with Mr. L. Richardson, E.G.S., other 

 confirmative fossils were found. Erom them there was evidence 

 not only for strata contemporaneous with the Cephalopod-Bed, but 

 also with the Cotteswold Sands ; these evidently formed part of the 

 so-called ' Upper Lias ' at Bredon Hill. But as the specimens 

 were only obtained from the fallen blocks in a gravel-pit, the actual 

 thickness of the deposits could not be ascertained. 



1 Bredon Hill is partly in Worcestershire, and partly in Gloucestershire. For 

 an account of the Aalenian deposits of the hill, see L. Richardson, ' Inf. Oolite 

 at Bredon Hill' Geol. Mag. 1902, p. 513. 



2 See, for instance, H. B. Woodward's ' Geology of England & Wales ' 

 2nd ed. (1887) p. 276. 



Q. J. G. S. No. 236. 2 k 



