72 A. Bell — Succession of the Later Tertiaries in Gt. Britain. 



The submergence of the north-west corresponds with the emergence 

 or elevation of the east, and in the Glacial beds thus exposed the 

 Thames river channel was opened, the oldest portion from East 

 London to Ilford, Grays and Crayford, opening southwards 

 (S. V. Wood), and at a later period, when the North Sea was 

 resuming its old bed [inhuming the Mammalian fauna, brought up 

 so frequently from its bottom by fishermen], the present channel 

 in its entire length opening eastwards. These earlier gravels and 

 brickeartbs yield a fauna indicating warmer conditions than now 

 or at any time since the preceding glaciation. Grouped with 

 these must be the rich Barnwell river gravels, containing more 

 extra-British freshwater and land shells than all the other Post- 

 Tertiary deposits put together, including Helix frvticum, the 

 only other Post-Tertiary locality for which shell is Stutton on the 

 Stour, a deposit of similar age, from whence the late Mr. S. V. 

 Wood, sen., obtained the specimen (the only one) figured in Mon. 

 Crag. Moll. I notice here this shell more particularly, because 

 I shall have to call attention to certain erroneous references 

 in respect to this species. The well-known deposit at Clacton 

 Cliff belongs to this series : and here I must demur to Mr. Dalton 

 collating the fauna at this place with that of Copford, especially 

 without due revision. The Copford shells were named by one of 

 the most competent men of his day, the late Mr. John Pickering, 

 from Dr. Gray's edition of Turton's Manual, and the Clacton list by 

 Mr. J. de C. Sowerby, in which two species are described as new, 

 one being from the figure a variety of Helix hispida, and the other, 

 judging from the description, a young Planorbis glaber. Mr. Sowerby 

 used a different nomenclature from Mr. Pickering, and the incorpora- 

 tion of both lists into one without the elimination of the synonymic 

 names unduly inflates the list of species (Memoirs of the Neighbour- 

 hood of Colchester, 1880). 



The Worcestershire Avon gravels may be assigned to this series also, 

 as, like the older Thames beds, the fauna of all kinds is marked not 

 only by forms of southern types, but by an almost complete absence 

 of northern and arctic species. The Musk Sheep would seem not 

 to be in accordance with this view ; but at present I should con- 

 sider its occurrence at Crayford, Eritb, and Fresbford near Bath, to 

 correlate these beds with the same age as the later Thames gravels 

 near Maidenhead, when the declining was gradual. The Thames 

 Valley is not a valley of one aspect or geologic stage, but many ; 

 the great river and its affluents, and the contents of the bordering 

 gravels and soils sufficiently attest this. Mr. Worthington G. Smith 1 

 points out that three stages at least in the manufacture of palaeo- 

 lithic flints are traceable, ranging from the crudest to delicate tools 

 of beautiful fabrication. 



Coincident with the river earths above referred to, is the ancient 

 peat of Lexden, near Colchester, where the Rev. 0. Fisher obtained 

 so many traces of mired and mud-bound Mammals, and an Insect 

 fauna of trans-pyrenean growth. 



1 Nature, xxvii. p. 270. 



