OF NORFOLK AND SUFFOLK. 315 



consists chiefly of greenish marl, with only a few stony beds. 

 Here the number of corals is so small, and the shells for the 

 most part are so comminuted, that the distinctness of the in- 

 ferior mass from the red crag is far less striking than on the 

 north of the river Deben. I caused a pit about seven feet 

 deep to be sunk in the yard at Tattingstone Hall farm, pierc- 

 ing the lowest part there exposed of the coralline crag, 

 through green marls, with intervening layers of flaggy lime- 

 stone, two or three inches thick. At the bottom of this pit I 

 found marl of the same character, containing a large Nucula, 

 Venus ovata, and some other shells; when the workmen were 

 stopped by the quantity of water which flowed in. One of 

 the flaggy beds of limestone was almost of a brick red colour, 

 and consisted chiefly of comminuted shells, like the green 

 marl. 



Although the upper crag at the point of junction is here 

 (at Tattingstone) very like the lower formation, yet we can 

 recognise it by the presence of Fusus contrarius, Turritella 

 terebra, and other shells which are wholly wanting in the 

 lower bed. 



Fluvio-marine Crag of Southwold, fyc. — Before offering 

 any general remarks upon the fossils of the coralline and red 

 crag, I shall pass on to the consideration of the crag of Nor- 

 wich, or "mammaliferous crag" as it has been termed by Mr. 

 Charlesworth, which is the principal object of this paper. — 

 By examining this crag in the neighbourhood of Southwold 

 and Norwich, I soon satisfied myself that instead of being of 

 purely marine origin, like the deposits already alluded to, it 

 is a fluvio-marine formation, containing everywhere an inter- 

 mixture of land, fresh-water, and sea shells, with the bones of 

 Mammalia and fish. I first examined this crag at Thorpe, 

 near Aldborough, where it extends to the sea-coast, I did 

 not observe its junction with the subjacent coralline crag, 

 but was informed by Capt. Alexander that the latter crops 

 out from beneath it upon the beach, where it is exposed for 

 200 yards at low water, being there called the "Thorpe rocks," 

 which are broken up for building stone. Sizewell gap, seve- 

 ral miles to the north, is the most northern point to which the 

 the coralline crag has yet been traced. But it is at Southwold, 

 about ten miles north of Thorpe, that the Norwich or fluvio- 

 marine crag is most largely developed. It may there be stu- 

 died both in a continuous line of sea-cliff, and in several large 

 pits scattered through the interior. It is very variable in mi- 

 neral composition, consisting of sand, shingle, loam, and la- 

 minated clay in regular strata, some of which bear marks of 

 very tranquil deposition. A thickness of about forty feet is 



