TIIK CRETACEOUS SYSTEM 481 



irregular layers of ironstone. This facies they preserve with little 

 change all round the Wealden area, and consequently the name of 

 Folkestone Beds is not a very happy one. In Sussex they include 

 thin Kinds of hard ferruginous grit, which is locally known as car- 

 stone. In Surrey and Hants they are from 130 to 160 feet thick, 

 but like all other members of the Vectian, they thin eastward 

 through Sussex, till near Eastbourne the whole stage appears to be 

 absent, and the Gault rests directly on the Weald Clay. 



The Sand-rock Group appears to be the representative of the 

 Folkestone Beds. It consists mainly of coherent sands with bands of 

 laminated clay, but contains no fossils. The carstone is a coarse 

 ferruginous grit which varies greatly in thickness, being 72 feet 

 thick at Redcliff, north of Sandown, but only from 6 to 12 feet 

 on the western side of the island. It contains rolled pebbles and 

 phosphatic nodules, and is considered by Mr. Strahan to be more 

 closely connected with the Gault than with the Vectian. 5 The fossils 

 found in it comprise Desmoceras Beudanti, Plicatula carteroniana, 

 and Lima parallela. 



When followed across to Dorset the Vectian is found to be 

 much reduced in thickness, being only 200 feet at Punfield Cove, 

 near Swanage, 136 at Worbarrow Bay, and 66 in Mupe Bay, 

 beyond which it is not seen. At Punfield the Atherfield Clay is 

 50 feet thick, and the upper part contains some remarkable fossils, 

 especially species of Vicarya, Natica, Actwon, Cerithium, and 

 Pleurotoma, which are common in the Rhodanian of Spain, but 

 have not been found elsewhere in England. 



2. Midland District 



The Wealden is not seen anywhere north of the Vale of 

 Wardour, and the sands and sandstones which emerge from beneath 

 the Gault in Berkshire, and thence at intervals northward to 

 Cambridge and Ely, seem to belong to the higher part of 

 the Vectian Group, nothing comparable to the Atherfield Clay or 

 the Hythe Beds having been observed in situ. 



Near Faringdon 6 (see Fig. 163) the Vectian consists for the most 

 part of soft yellow and brown sands, with some layers of sandstone 

 and thin bands of ironstone, but at the base there are irregular beds 

 of pebbly, fossiliferous gravel, compacted in places into aconglomerate. 

 The pebbles are chiefly of quartz and porcellanous slate (lydianite). 

 Among the fossils sponges, Brachiopods, and Echinoids are con- 

 spicuous, the following being some of these : 



Terebratula tornacensis. Peltastes Wrighti. 



,, depressa. Cidaris faringuonensis. 



Waldheimia tamarind u>. Raphidonema porcatum. 



2 I 



