316 RELATIVE AGES OF THE CRAG 



sometimes exposed in one section, as in the cliff at Easton 

 Bavant, about three quarters of a mile N.E. of Southwold. — 

 The marine shells are here spread through a thickness of ten 

 and sometimes fifteen feet, chiefly in the lowest part of the 

 deposit here laid open. Some of the bivalves, as the Nucula 

 Cobboldia, Tellina obliqua, and Mya arenaria, have both 

 valves united, and have not suffered by attrition, although as- 

 sociated, not only with land and freshwater shells, but with 

 rolled fish-bones, and the bones and teeth of Mammalia, as 

 of the elephant, rhinoceros, horse and deer. Capt. Alexan- 

 der, whom I was so fortunate as to have as my guide, inform- 

 ed me that in one bed at the base' of the cliff, which is most 

 rich in marine shells, and which is only from four to six inches 

 thick, he found the tooth of a horse, buried with sand, in the 

 mouth of a large specimen of the Fusus striatus. I learnt 

 from the same gentleman, that the bones of Mammalia are 

 frequently met with in the same bed as those of fish, marine 

 shells, and Crustacea ; and in more than one instance I was 

 enabled myself to verify this fact. He also showed me the 

 tooth of a Mastodon, washed out of the cliffs between Dun- 

 wich and Sizewell, which may, without hesitation, be refer- 

 red to the same formation. 



In tracing the fluvio-marine deposit from the cliffs of Eas- 

 ton Bavant to the northward, in the direction of Kessingland, 

 I found distinct layers of flinty shingle regularly interposed 

 between the shelly beds, so that I have no hesitation in refer- 

 ring to the Norwich crag those strata of sand and shingle on 

 this coast, which so much resemble the sandy portions of 

 the plastic clay of the London and Hampshire basins. 



I examined, with Capt. Alexander for my guide, several 

 inland pits of Norwich crag near Southwold; and in one of 

 these in the parish of Henham, on the property of Lord Strad- 

 brooke, I picked up mammiferous bones and teeth, from an 

 undisturbed bed containing marine, freshwater, and terrestrial 

 shells. Among the freshwater shells I found a species of 

 Cyrena, which appears to be one of the varieties of that va- 

 riable species, Cyr. trigonula, found at Grays in Essex, and 

 elsewhere. In each of the different localities of this neigh- 

 bourhood, as in those of the red crag of Suffolk, some shells 

 are found which are not met with at other spots ; the whole 

 assemblage, however, agrees very closely with that derived 

 from the pits around Norwich, to the consideration of which 

 I shall now pass. 



Crag near Norwich. — The crag of the neighbourhood of 

 Norwich is interposed, in patches of variable thickness, be- 

 tween the chalk, on which it rests, and a dense bed of gravel 



