30 Mr. Rose’s Sketch of the Geology of West Norfolk. 
near Swaffham, the gravel beds contain so large a quantity 
of decomposing iron pyrites, that the water percolating the 
gravel is sufficiently charged with iron to cement the sand 
and stony fragments together, and form a coarse breccia. 
Under similar circumstances, the water of some springs has 
a considerable ferruginous impregnation : at Thetford a chaly- 
beate spring occurs, containing also carbonate of soda and 
free carbonic acid, with a proportion of zvon not inferior to 
that of Tunbridge Wells, although it flows from a very dif- 
ferent source; the elaboratory of ow chalybeate being situated 
in the diluvial beds, and the decomposition of iron pyrites 
from the disrupted chalk strata affording the ferruginous in- 
gredient. 
Fragments of calcareous tufa are occasionally met with in 
these beds. i 
Being desirous of not extending this paper beyond the li- 
mits of a periodical, I forbear noticing the ceconomical and 
agricultural purposes to which these beds are applied; and 
for the same reason I shall refer your readers to Mr. Samuel 
Woodward’s Geology of Norfolk* for a list of the antedilu- 
vian organic remains, which are, for the most part, inclosed 
in boulders. 
The only mammalian remains I have seen are, part of a 
tusk of Elephas primigenius found at Hunstanton, teeth and 
vertebrae of Elephas Indicus from beneath the brick-earth at 
Narford, and part of a tooth of the Mastodon latidens? found 
in a gravel-pit at Swaffham. 
It is worthy of notice, that the parent strata from which 
the boulders must have been originally detached are all si- 
tuated to the north and the west of our county. 
Alluvium. —The first deposit I shall notice under this head 
has received the name of * Brick-earth of the Nar,” from my 
having (till very recently) found it only in the valley through 
which that river takes its course. In this valley I have traced 
it west and east from Watlington through East Winch and 
West Bilney to Narford, a distance of nine miles. It occupies 
low grou d, except at its inland extremity, where it rises to 
about eig"ty feet above the level of the Nar. 
Mr. Arthur Young in his “ Agricultural Survey of Nor- 
folk,” speaking of this deposit, under the article “* Manure 
Oyster Shells,” says, “In East Winch and West Bilney, and 
scattered for ten miles to Wallington (Watlington ?), there is 
a remarkable bed of oyster-shells in sea mud: the farmers use 
them at the rate of ten loads an acre for turnips, which are a 
very good dressing; they are of particular efficacy on land 
* An Outline of the Geology of Norfolk, page 39, “ Clay of Western 
Norfolk,” 
