Yol. 57.] OF THE NORTH COTTES WOLDS. 129 



otherwise the Upper Trigonia-grit would have beea deposited in 

 the hollows. I was indisposed, however, to accept this argument, 

 because the hollows found were so slight (they have only a fall 

 of 7 feet per mile) that the surface would have been sufficiently 

 horizontal to allow of the Upper Trigonia-grit resting there. 



But there are other points to be considered besides the matter 

 of consolidation. I have now found, by researches over a larger 

 area, that the denudation of Jurassic rocks affected both England 

 and Isormandy, and that so far as the South-west of England is 

 concerned, the lines of denudation fall into a fairly definite series of 

 curves. Therefore I am inclined to accept, and very gratefully to 

 acknowledge, Prof. Groom's suggestion. And I would put the 

 matter in this way. During the deposition of the Bajocian, and 

 at other times, small earth-movemetits occurred which threw the 

 Jurassic rocks into folds of extremely slight elevation, in, probably, a 

 very shallow sea. The anticlinal folds were denuded, and thus the 

 edges of various deposits were cut across, exposed, and bored, and 

 upon the surface so formed a deposit such as the Upper Trigonia- 

 grit was laid down. 



There were evidently two such periods of earth-movement and 

 denudation during the deposition of the Inferior Oolite of the 

 Cotteswolds,^ — one after the deposition of the Upper Freestone ; 

 another after the deposition of the Ph{llij)siana-\)eds. The latter 

 was the most important : it extended into Normandy. At Sully, 

 near Bayeux, are pebbles containing ammonites of the Sauzei- 

 Witchellice hemerse — date of the Phillijysiana-to-WitcTiellia-'beds of 

 Cleeve Hill. Then at the base of the ' Oolithe ferrugineuse' is a kind 

 of remanie deposit with Stepheocerata ; and then deposition proper 

 commences with the ' Oolibhe ferrugineuse ' of the niortensis 

 hemera — that is, it commences at an earlier date than in the 

 Cotteswolds, for the Upper Trigonia-gvit is one hemera later, 

 namely Oarantiance. Still the recommencement is only local in 

 Normandy. About 7 miles away from Sully, between Port-en- 

 Bessin and Ste. Honorine des Perthes, there is no ' Oolithe fer- 

 rugineuse,' — the recommencement of deposition started with strata 

 of Truellii hemera. The advance of deposition was slowly 

 towards the north-west, indicating where the anticline might be 

 expected. 



III. Generalized Section of the North Cotteswolds. 



A generalized section of the deposits found in the main mass of 

 the North Cotteswolds may now be given, and then the details of 

 the different sections which afforded the evidence whereon it is 

 constructed. 



^ Similarly in Somerset and Dorset ; see Appendix II, p. 153. 

 Q.J.G.S. No. 225. k 



