18 S. V. Wood, Jim. — American and British Surface- Geologp. 



the clay, up to elevations exceeding 300 feet in tbe Eastern Moor- 

 lands of Yorkshire. From information, also, given me by Mr. 

 Topley of the Geological Survey, the same beds appear to be re- 

 presented partly in the form of an upper clay with boulders, and 

 partly in the form of gravels that have derived their debris from the 

 Cheviots, which occur over the lower elevations of Northumberland, 

 i.e. over the plateau country which forms the eastern portion of that 

 county ; and in all probability they extend into Scotland. Similar 

 beds in the form of a (so-called) Middle Sand and Upper Boulder 

 (Brick) clay with occasional boulders extend over the lower ground 

 intervening between the Pennine chain and the coast in Cumberland, 

 Lancashire, and Cheshire ; and they reach along the north-west 

 coast as far south at least as the north of Carnarvonshire. Prob- 

 ably also the sands and clays of the Severn Yalley containing marine 

 mollusca of similar recent character to those found in the Hessle 

 and Fen gravels, and in the upper clay and middle sand of the 

 north-west, which have been described by Mr. Maw (and the shells 

 of which he kindly sent me for examination), belong to the same 

 period. The southern limit of the Hessle clay appears to be at 

 Firsby, on the northern edge of the Lincolnshire Fen ; and, so far 

 as I know it, the southern limit of the upper clay of the North- 

 west of England appears to be at the same latitude in the Menai 

 Straits, but on the eastern side the gravels of the formation carry 

 the submergence a little further south, viz. over the Cambridgeshire 

 Fen.i 



On both sides of England, therefore, a similar degree of re- 

 frigeration and limited submergence, giving rise to these beds, 

 seems to have occurred ; this submergence (not the glaciation) 

 shading off southwards to evanescence on the eastern side be- 

 tween lat. 52° and 53°; but on the west it may have extended 

 further. The gi-avels of this formation, which in the Cambridge- 

 shire Fen extend southwards to about lat. 52° 30', are there and 

 over the Fen northwards uncovered by Boulder- clay, ^ but in 

 Holderness they are so covered. The marine molluscan fauna of 

 these gravels differs in character from that of the East Anglian 

 Glacial beds, in that it contains none but species which live either 

 in British seas or in the seas immediately north of the Shetlands, 

 whereas the Glacial beds of East Anglia contain some species that 

 are unknown living, and others which, if living, are represented by 

 species not known as such nearer than the North Pacific. Inter- 

 mingled with the mollusca of these gravels both in Yorkshire and 



^ The distribution of this (Fen) gravel along the northern edge of the Fen and 

 where it approaches near to the Hessle clay is shown in the map, and its position 

 relatively to the chalky clay in section xv. 



" A stony clay, a few feet thick, which covers unconformably the Lower Glacial 

 formation on the Norfolk coast, between Mundesley and Eccles (lat. 52" 48' to 52° 51'), 

 and which there rises to an elevation of about 40 or 50 feet above Ordnance 

 datum, seems to belong to this formation. The molluscan fauna of the Hessle gravel 

 and its equivalents in the East of England are given in the tabular list to the sup- 

 plement to the " Crag Mollusca," in the volume of the Palseontographical Society 

 for 1873. 



