36 Mr. Rose’s Sketch of the Geology of West Norfolk. 
pressa, and Turbo ulve; this bed was not cut 
through*. 
In the beds Nos. 2 and 4, fluviatile shells were found: the 
smaller ones appear to have been overlooked by the labourers, 
but Anodons were noticed, and were found interspersed 
throughout both beds; in No. 2. they were abundant, forming 
a layer immediately upon the peat, No. 3. 
The shells from No. 6. are certainly not of the same era 
as those of the brick-earth of the Nar; they are evidently of a 
more recent date, and resemble those now existing in the 
river at Lynn. 
At Mr. Allen’s well, in the town of Lynn, similar alluvial 
strata to those at Eau-brink were met with, and were imme- 
diately succeeded by a bed of blue clay containing nodules of 
chalk, between 20 and 30 feet in thickness, which we consider 
to be diluvium. 
For the section of the alluvium at Denver Sluice see a former 
part of this paper, vol. vii. p.173. By the above sections we 
are informed of, and are enabled to arrange, the succession of 
changes to which Marshland has been exposed. Commencing 
with the period of the irruption of the sea, and its residence 
in Marshland, during which the marine exuvie discovered in 
making the Eau-brink Cut were deposited, we learn next that 
this district became a marsh, in which alders, hazels, and marsh 
plants vegetated. Its next change was inundation by fresh wa- 
ter, forming a lake inhabited by freshwater Testacea, a transi- 
tion probably effected by obstruction to the outlet of the rivers 
of the great level, from bars thrown up by the tidal waves in 
the estuary now called the Wash; this state continued till the 
deposition of eight feet of mud had elevated its surface, and, 
with the aid of other natural forces, burst its barrier; again the 
waters escaped, leaving, perhaps, but a solitary river to drain 
the interior ; again aquatic plants took possession of the surface, 
and from the occurrence of large trees in the peat (No. 3.), 
forests of oak and other trees indigenous to this island sprang 
up, encompassed by brush-wood of hazel, alder, &c. This 
was the state of the fens at the period of the Roman invasion; 
and after the invaders had established their authority in the 
country, they commenced embanking this district, to protect 
it from the inroads of the sea }: itis said, that the Emperor Se- 
* Marine silt containing similar shells occurs in Lewes Levels. (Dr. Man- 
tell’s Geology, &c.) 
+ Tacitas, in his life cf Agricola, says, “ the Britons complained that 
their hands and bodies were worn out and consumed by the Romans, in ~ 
clearing the woods, and embanking the fens.” 
