118 
RED AND NORWICH CRAGS. 
beds in which it was deposited. At Coltishall mammalian 
remains have been found in the pebbly gravel overlying the clay- 
beds. 
The evidence shows that the bones may belong to the period as 
much as the shells which occur abundantly in the Stone Bed and 
in crevices of the underlying Chalk. Although perhaps com¬ 
prising relics of some old land-surface destroyed during the 
formation of the Crag, it is hardly possible that the Stone Bed 
represents an ancient soil, or that any portion of the Chalk itself 
is an old land surface. At Postwick the surface of the Chalk, as 
is well known^ is bored by marine shells and annelids; and at 
Bramerton the presence of Pholas-burrows has also been pointed 
out. 
The Stone Bed is therefore part of the Norwich Crag. Its 
formation was very likely somewhat analogous to that of the 
coarse flint foreshores and sea-beds found near • Cromer and 
Trimingham, where the flints are worked directly out of the 
Chalk. Hence it may be of slightly different ages as the Crag sea 
encroached further and further. 
The Mastodon it is true indeed lived in earlier times than those 
of the Norwich Crag, and its remains might have become em¬ 
bedded in some previous freshwater or lacustrine deposit, whose 
destruction, as suggested by Mr. Harmer, yielded the remains 
found in our Norwich Crag ; and yet it may Imve lived on to Newer 
Pliocene times, and remains of the animal, thrown on the beach, 
may have been in some cases mpidly covered up and preserved. 
From the state of preservation of the specimens in Mr. Fitch’s 
collection, Mr. E. T. Newton was of opinion that they could not 
have been derived but belonged to animals that had lived in the 
Crag period. 
A few of the more interesting of the sections in the Norwich 
area will be selected to illustrate the singular variability of the 
deposits, for though by taking particular pits as types we can 
subdivide the Crag into apparently well-marked zones, yet a series 
more truly Illustrating the character of the Norwich Crag will 
show how impersistent are these zones, and how little reliance 
can be placed on mere lithological changes. It should not be 
forgotten also that the whole of the Pliocene strata of this district 
are essentially of shallow-water or littoral origin, and that such 
deposits, from the nature of their origin, must always be extremely 
variable. 
Continuing to follow northward the exposures of the Crag we 
will take first the Valley of the Tese. Here Pliocene beds out¬ 
crop for a long distance, but most of the sections are of little 
terest and are sparingly fossiliferous. It will therefore only be 
necessary to mention one or two of them—the rest will be found 
fully described in Mr. H. B. Woodward's Memoir. 
The most southerly of the fossiliferous pits in the Tese Valley 
occurs at Tharston Furze Hill, about one mile south of Flordon 
Station. Above the Chalk was seen the stone-bed, and this was 
