ON THE ALLUVIUM OF THE BEDFORD LEVEL. 
81 
been recently found in Bardolpli fen ; rat [Arvicola amphibia) ; I 
very lately met with a lower jaw of tlie water-rat at tlie brick- 
yard at Lynn : and the beaver {Castor fiber), part of tbe bones of 
the head^ with the incisor teeth in situ, were taken np at Little- 
port in the Isle of Ely. The marine shells of the upper beds 
consist chiefly of Mactra stultorum, Lutraria compressa^ and 
Cardium edule*; the fresh -water include most of the species of 
Luimea, Paludina, Helix_, Planorbis, and Cyclas usually met with 
in the ponds and ditches of the district ; the only land shell that 
I have at present received from these beds is Helix aspersa. 
In tracing the succession of geological phenomena which have 
occurred on the scite of the " Great Level/^ and rendered mani- 
fest by the preceding observations and sections_, I will commence 
at the period of the emergence from the ocean^ of what is now 
the eastern portion of England, for I consider, at that epoch, this 
country was a part of the great continent of Europe. In the 
first place then, I am led to believe, from the preceding data, 
that about the period of the emergence, anterior to it, a great 
debacle, the geological deluge, rushing southerly, swept over the 
out-crop of the Kimmeridge clay, and carrying onward with it a 
considerable thickness of that stratum, deposited it again through- 
out a considerable distance in its southerly course ; I am led to this 
conclusion, from having met with the " drift, of biue clay, con- 
taining the fossils from the Kimmeridge bed in the line of the 
lesser Ouse and Waveney rivers at Thetford, Lopham, Diss, 
Scole, Oakley, Worlingham, and Pakefield on the coast of Suf- 
folk. The same debacle brought the chalk from Yorkshire, de- 
positing it in nodules, and intermingling it with the surface clay 
of the Oxford and Kimmeridge strata, forming the diluvium,^' 
as seen in stratum 5 of section 4 at Lynn, but still leaving a 
* Thompson, in his History of Boston, page 277, says, " In the East and West 
Fens at the depth of seven or eight feet, between the peat stratum and the sand 
or clay below are in many places considerable quantities of cockle shells." 
