478 STRATIGKAPHICAL GEOLOGY 



known as the "lobster bed," from the occurrence of Meyeria 

 magna. Other fossils found in these beds are Hoplites furcatus, 

 Hop. leopoldinus, Hop. Deshayesi, Gorbis corrugata, Pinna robin- 

 aldina, and Enallaster Fittoni. 



Hythe Beds. In Kent, between Hythe and Sevenoaks, these 

 beds consist of greenish-yellow sand, often marly or argillaceous, 

 and hard bluish-grey calcareous sandstone, the soft beds being 

 locally known as hassock and the hard beds as rag ; the latter 

 being known as Kentish rag. The beds of rag and hassock 

 alternate in regular layers. 



From Hythe to Maidstone the thickness of these beds is only 

 from 70 to 80 feet, but they increase rapidly westward and are 

 160 feet at Sevenoaks, and still thicker in Surrey. This increase 

 of thickness is mainly due to the incoming of an upper set of 

 sands with frequent layers of brown chert. These upper beds 



Fig. 160. SECTION THROUGH THE LOWER CRETACEOUS SERIES NEAR DORKING. 



Distance 8 miles. 



8. Middle and Lower Chalk. 5. Folkestone Beds. 2. Atherfield Clay. 

 7. Malmstone and sand. 4. Sandgate Beds. 1. Wealden Beds. 



6. Gault marls and clays. 3. Hythe Beds. 



attain their maximum thickness about Eeigate, Dorking, and 

 Leith Hill, where the lower group of soft ferruginous sand is from 

 100 to 130 feet, and the cherty beds are also in places over 100 

 feet thick. The Hythe Beds maintain this facies all round the 

 western end of the Wealden area, but thin rapidly eastward 

 again as they are traced along the southern border, disappearing 

 entirely near Lewes. 



The chief fossils of the Hythe Beds are Terebratula sella, 

 Exogyra sinuata, Trigonia spinosa, Tr. ornata, Actinocamax bruns- 

 vicensis, Nautilus pseudelegans, Ancyloceras Bowerbanki, Mac.ro- 

 scaphites gigas, Hoplites Deshayesi, and Holcostephanus Hambrovi. 



Sandgate Beds. These are a variable set of beds, but are 

 generally more or less argillaceous. At and near Sandgate (see 

 Fig. 161) they consist of dark-green clayey sand full of glauconite 

 grains and about 70 feet thick. Fossils are not numerous, but at 

 the base, resting on the Hythe Beds, there is frequently a layer of 

 pebbles and phosphate nodules, with Brachiopods and other fossils 

 in the state of casts. 



