and on the Chalk of Norfolk and Suffolk, 5fc. 375 



ammonite, teredines in indurated clay^ plagiostomae, pernae, modiolae, pyritous 

 fossil-wood^ and hard orbicular septaria containing in their interior nautili or 

 ammonites^ much distorted by the crystallizations in the septa. With these 

 occur, near Svvaffham in particular, boulders of hard chalk, containing two 

 species of belemnite, together with smooth and plicated terebratulae, and 

 maraillated echini. In the light lands in the neighbourhood of Svvaffham is an 

 abundance of flinty nodules, containing alcyonia and sponges, and marked 

 with impressions of echini and their spines, inocerami, and terebratuhe. 

 Upon the high edge of the chalk, at Marham, within a quarter of a mile of its 

 western termination, we find in a very stiff alluvial yellow clay large blocks 

 of a green sandstone, in which are imbedded Pecten orbicularis and P. cor- 

 nea, Terebratula lata and T. ovoides, Trigonia aliformis, a species of Lutra- 

 ria, pectunculi, and belemnites. In a mass of ferruginous sandstone found 

 in the same neighbourhood, and belonging probably to these alluvial deposits, 

 the fusiform belemnite with its alveolus, and two species of Pecten, have 

 been discovered. 



Over the chalk at Norwich, and to the north and west of the city, are 

 thick beds of sand and gravel, with patches of alluvial clay and brick-earth 

 interspersed. The sand, except where the crag-shells rest immediately on the 

 chalk, seldom contains many or very perfect organic remains. The brick- 

 earth yields only a few water-worn belemnites. The flints in the gravel are 

 brown, gray, and (near the surface) colourless. They are shattery, breaking 

 into fragments with the slightest blow of the hammer ; and hence they are 

 unfit for masonry or the fabrication of gun -flints, though unrivafled as a ma- 

 terial for the repair of roads. On breaking the large gravel-flints found near 

 the surface, both surfad^s of the fracture are often seen lined with dendrites. 

 Poringland hiU and Mousehold heath, near Norwich, furnish an abundance 

 of these arborizations. These flints contain the usual fossils of the chalk 

 with layers of flint, as well as some others which have not hitherto been found 

 in that stratum. Such detached fossils as are found, are usually silicified casts 

 the calcareous matter of the shells having disappeared. Thus of the belem- 

 nite, a flinty cast only of the cavity of the alveolus remains. The other 

 detached fossils are trochi, inocerami, terebratulae, pectines, plagiostomae, 

 cardia, serpulae, echini, alcyonia, &c. 



2. On the Chalk. 

 The most easterly point at which chalk has been traced, is on the coast, 

 between Mundesley and Cromer, where we find two detached masses of soft 



VOL. VI. 3 c 



