The Lower Cretaceous of the Vale of Wardour. 293 



One of the ferruginous layers in the sands has yielded a fairly 

 good specimen of Exogyrn sinuata, which is one of the most 

 characteristic fossils of the Vectian group. 



In this well the base of the group is evidently not reached, but 

 most fortunately it is completed by a brook section at Teffont, which 

 begins in a black clay exactly like that found at the bottom of the 

 well. This black clay is about six feet thick, and passes down into 

 a nearly black sand which has a green streak when cvit, and consists 

 mainly of dark-green grains of glauconite. 



Underneath this sand are mottled clays, which were recognized 

 by Mr. Whitaker as similar to the " catsbrain " clays of the Weald, 

 — their tints are yellow and white, mottled here and there with 

 a rich claret-coloured stain, which imparts a special character to the 

 clay. Below are yellow loamy clays. We consider these to be of 

 Wealden age, and the dark sand to be the base of the Vectian ; but 

 as the section is not clear, and this sand has not yet been found 

 elsewhere, we cannot say whether the sand is conformable to the 

 clays or not. 



The maximum thickness of the Vectian appears to be about forty 

 feet, and the yellowish-green sands which underlie the pebbly base 

 of the Gault can be traced westward for several miles both along 

 the southern and the northern sides of the Vale, overlapping the 

 Wealden and the several divisions of the Purbeck beds, and 

 gradually thinning out. 



The thickness of the Wealden clays is difficult to estimate, because 

 exposures are so few and the slopes are so gentle ; but there can 

 hardly be more than 40 or 45 feet at the east end of the vale, 

 and they thin out rapidly towards the west, not extending far 

 beyond Teffont on the north side, nor far beyond Sutton Eow on 

 the south side. 



Eastward the Wealden occupies a certain width of flat ground 

 ■which merges into the alluvium east of Dinton Station. At the 

 cottages north of the station a well was sunk for about forty feet 

 through yellow-grey and brown clays. We were informed that 

 there was a perfect succession of clays without any sudden change 

 or any pebbly bed, but that at the bottom there was a floor of very 

 hard sandstone. The accuracy of this information we proved by 

 having the well emptied, and the bottom tested with a punch. A 

 piece of this sandstone was given to one of us by the well-sinker, 

 and is a hard grey calcareous grit with Cypridea punctata. The 

 material thrown out of the well also yielded Cyprides, Paludina 

 carinifera, and Unios. We believe these clays to be of Upper 

 Purbeck age, for the lower part of them, with a band of calcareous 

 grit, exactly like that in the well, can be seen in the first cutting 

 west of the station, and they are succeeded by a set of clays, marls, 

 and thin limestones, which have a much greater resemblance to the 

 Purbeck beds than to the Wealden. 



When the railway was made there must have been an excellent 

 section of these beds and the upper part of the Middle Purbecks in 

 the two cuttings west of Dinton Station; now they are so over- 



