Mr. R. C. Taylor on the Geology of East Norfolk: 283 



discoveries in the minuter genera of shells, naturalists are en- 

 abled readily to determine, whether such do in reality belong 

 to the class of living shell-fish ; or, if otherwise, what are the 

 proportions it exhibits between those which appertain to the 

 recent and the extinct species. Nearly the whole of the shells 

 contained in this catalogue are accurately figured in Sowerby's 

 Mineral Conchology, from specimens collected at this spot ; 

 and all are unquestionably similar to those which characterize, 

 and are peculiar to the crag; or, as it is properly called, the 

 upper marine formation. It is extremely probable, that up- 

 wards of one half of those enumerated have no recent ana- 

 logues, and the practised eye of a skilful concliologist will de- 

 tect varieties in many that appear to assimilate to those now 

 living. At the same time it must be remembered, that they 

 are associated with the remains of herbivorous animals, which 

 have never been known in the present state of our globe, — 

 the mastodon, the elephant, the gigantic elk, and the enormous 

 horned bison. Their regular becls contain no works of art ; 

 no traces of the human species*. The British Museum con- 

 tains a tooth of the mastodon, in which the enamel is con- 

 verted into opal. This fine specimen is figured in Smith's 

 " Strata Identified," and was discovered with horns of deer, 

 at Whitlingham, in that same stratum of crag shells, described 

 by Mr. Robberds. 



In general, the fossils of this formation are not minera- 

 lized, but are very fragile. In Suffolk and part of Norfolk 

 they are chiefly deposited in dry loose beds of sand, which 

 are slightly consolidated and discoloured by iron. Thus 

 at Languard Cottage, some curious artificial caverns have 

 been formed in a thick bed of these shells. Where they oc- 

 cur in clay, they are partially mineralized ; their surfaces are 

 smooth, and sometimes glossy. At Whitlingham and upon 

 the north-west coast of Norfolk, they are occasionally seen 

 resting immediately upon the chalk, mixing with its flinty de- 

 bris, and even having their cavities filled with chalk. Horns 

 ot stags are frequendy found under the same circumstances, 

 embedded in chalk marie, particularly along the sides of the 

 Norwich valley, extending between Hellesdon and Cantley. 

 In Essex, similar shells occur in a strong blue clay. Near 

 Orford, in Suff"olk, they are mixed with interesting varieties 

 of coral and sponges, forming a soft porous rock used for 

 building. In some other parts of its course this formation 



* The rudely-shaped flint axes which have been discovered in the peaty 

 bed of the Waveney Valley, arc among the most ancient monuments of man 

 in this island. They must be classed with the extraneous alluvial substances 

 of our highest valleys. 



2 O 2 assumes 



