INTRODUCTION. XXI1X 
south than Steeping, in Lincolnshire, on the opposite side of the Wash, and about 20 miles 
west of Hunstanton; neither does the Cyrena occur in it.’ 
The March gravel occurs around March railway station, and in pits in the town 
itself. It isin the midst of the Cambridgeshire Fen,” and there are no means of testing 
geologically its position, as it forms but small islands rising out of the recent peat and 
alluvium of the great level of the Fen. It is very rich in individuals of Mollusca, which 
are in good preservation, and its fauna, so far as yet known, resembles that of Kelsea and 
Hunstanton in consisting entirely of species now living, and which, with two exceptions, 
still inhabit British seas. In all these gravels, as well as in the Nar Brick-earth, Ostrea 
edulis, which is absent from all the East Anglian and, indeed, from all the English glacia] 
beds,? is abundant; and there can be little doubt that the four are synchronous and 
belong to the earlier, or Oyrena fluminalis part of the Post-glacial period. 
The fifth fossiliferous marine Post-glacial formation referred to, is that of the Brick- 
earth of the Nar Valley, in north-west Norfolk, which occurs at Kast Winch, Bilney, 
Pentney, East Walton, Tottenhill, and other places. Our knowledge of the Mollusca of 
this formation is wholly due to the late Mr. C. B. Rose.* Its fauna, like that of the gravels 
of Kelsea Hill, Hunstanton, and March, consists entirely of species still hving, and which, 
with one exception, occur in British Seas. The shells of this formation are in fine 
preservation ; and there can be little doubt of the deposit being one of an estuary connected 
with that sea, which a Post-glacial depression, shown by the Hessle beds, caused to 
overflow the lower elevations of the eastern side of England. 
The clay XI, shown in Sections I and II as capping Hasboro’ Cliff, is a deposit of 
not more than four or five feet in thickness and is unfossiliferous. It seems destitute of 
chalk, but is full of small stones, chiefly flint; and rising from the sea level at Eccles 
Cliff, it dies out at an elevation of about fifty feet along the coast between Bacton and 
Mundesley. It is not improbable that it may be synchronous with the Hessle clay, 
although, at present, we are without the means for a satisfactory comparison.” 
1 Oyrena fluminalis, however, occurs in the fluviatile deposit of Barnewell, in Cambridgeshire, which we 
regard as coeval with the March and Hunstanton marine beds. 
2 Similar fossiliferous gravel occurs at other places in the Fen, such as Whittlesey, Wimblington, and 
elsewhere. 
3 In some earlier papers by us this shell was given from the Middle Glacial, but it was a mistake. 
4 See ‘Geol. Mag.,’ vol. ii, p. 8, and the prior papers there recited. A list of the Mollusca is there 
given by Mr. Rose, to which should be added Nassa pygmea. 
5 This clay obscures the surface of the low country for some miles south-east of Hasboro’ so as to render 
the mapping of that part uncertain. Whether it has been mistaken on the Hasboro’ Cliff for the Great 
Chalky clay, No. 9, we know not; but we do not recognise this latter clay either at Hasboro’ or anywhere 
else along the North Norfolk coast section, though it occurs on the East Norfolk coast from Caistor to 
Winterton. On the top of Dunwich Cliff (Section R) there occurs a Post-glacial bed, from three to seven 
feet in thickness, consisting of a loam which in places contains some fragments of the clay, No. 9. This 
may, perhaps, be the same as the capping clay, XI, of Hasboro’. It is shown in Section R under the same 
