Part of Gloucestershire and Somersetshire. 365 



of bivalve are particularly abundant,, apparently derived from a Tellina or a 

 Donax. And in the sandy limestone No. 7, I have observed a few fragments 

 of small boneSj of an indeterminate character. 



This formation of sandstone is bounded by the carboniferous limestone on 

 every side^ except on the north-eastern declivity^ where the calcareous con- 

 glomerate prevails ; but its position with respect to those formations is not 

 distinctly shown by actual contact in that quarter. From the extended re- 

 searcheSj however^ of the Rev. VV. D. Conybeare and Professor Buckland^ it 

 appears evidently to be of later origin than either of them; since in a direction 

 more toward the south-east^ two small eminences of a similar sandstone are to 

 be observed, reposing upon the calcareous conglomerate that partly covers 

 Mendip adjacent to the defile leading to Charton Mendip : — a view, which has 

 since been confirmed by my own personal investigation. The three eminences 

 of cherty sandstone, therefore, though of rather doubtful relations, may per- 

 haps be considered as most nearly allied to the iron and green-sandstone forma- 

 tion, and as outlying portions of that which is found in the regular order of 

 succession above the oohte, in the east of the county, and in the adjoining- 

 parts of Wiltshire. 



§ 45. Prom the north-eastern front of Mendip, between Blagdon and Bur- 

 rington, the calcareous conglomerate extends quite across the valley to the 

 north ; acquiring in the higher strata a finer grain, and passing into a compact 

 Hmestone often of an earthy aspect, which forms beds of an argillaceous, 

 sandy, or magnesian quality, that support and in some places alternate with 

 the marl and clay of the new red sandstone formation : — which last, on the other 

 hand, is succeeded in part by shelly lias limestone; as in the top of the isolated 

 ridge of Aldwick, on the north side of the Yeo, where the stone is in hori- 

 zontal strata, and has the aspect of a congeries of broken shells. The new 

 red clay-marl in the lower part of that ridge, on which Aldwick Court is built, 

 contains, as I am informed by Mr. Baker the proprietor of the estate, a con- 

 siderable bed of white granularly-foliated gypsum. 



On the northern side of the valley, the calcareous conglomerate is again 

 seen in contact with the carboniferous limestone, flanking the Broadfield 

 Down range on its south-western side, but declining from thence into the vale 

 toward Wrington and Congresbury. It forms the eastern border of that range 

 also in the direction of Butcombe and Winford, and again at the western base 

 of the Dundry range, extending thence toward the vale of Ashton. Toward 

 the Bristol Channel, the new red clay marl is found sustaining lias, in Wolvers- 

 hill between Banwelland Worle, and in the vicinity of Locking and Weston: 

 and the same fact may be observed, in the eastern direction, in the low hills 

 which lie between the parallel of Butcombe, Winford, Dundry, and the Avon, 



