and Phenomena of the County of Suffolk. 363 



dip and inclination of the crag agree with those of the London clay, and 

 therefore I infer, that both were denuded by the same currents, and while they 

 were beneath the level of the sea, and that they were equally acted upon by 

 the same elevating movements. According to my observation, the deposit 

 nowhere extends beyond twelve or thirteen miles from the coast, and at Pake- 

 field, where the diluvial clay comes to the very edge of the sea, it disappears 

 as a surface deposit, but re-appears at intervals further north between that point 

 and Cromer. Though crag is undoubtedly discoverable here and there, in 

 situ, as a regular formation north of the Waveney, yet I by no means allow 

 that it is regularly stratified as an undisturbed deposit between Leiston and 

 Pakefield. I am fully convinced, from observation, that the diluvial clay and 

 crag are distinct deposits ; and I am almost equally convinced that, if the crag 

 has any share in the formation of the cliffs between the Blithe and Lake 

 Lothing, it has been affected by disturbances of a similar nature to those 

 which are presented in the cliffs of East Norfolk. That the crag may have 

 occupied the localities, there is no reason to deny ; but they now present no 

 traces of an undisturbed deposit. 



To the previous descriptions of the structure of the crag, I have nothing to 

 add, except that where the shells are not visible, the sands contain a slight 

 mixture of calcareous matter. 1 object to the separation of the beds with shells 

 from those without ; as the shifting of a sand bank would correctly account 

 for the occasional occurrence of beds thirty feet thick resting upon strata in- 

 closing teslacea. 



Believing that the true rationale of the crag is to be found in the hypothesis 

 of sand banks inhabited by testacea, and situated in a tidal way exposed to 

 violent fluctuations of the sea, as well as subject to drifts of extraneous matter 

 from land waters, I see nothing extraordinary in the idea that accumulations 

 of sand and shingle may have formed a part of that deposit in which the crag- 

 is regularly stratified ; but I cannot consent to such accumulations, though con- 

 temporaneous with the crag, being classed with it under that name; much less 

 can I consent to diluvial clay being also included in it. 



If, then, we assume that in the tertiary sea sand banks were formed, around 

 the shelves and under the lee of which testacea collected, lived and died, as at 

 present, many of the phasnomena of the crag may be readily solved ; and we 

 shall not need to wonder why the bivalve shells are found lying with the flat 

 sides to the strata of sand, why the young are congregated in one group and 

 the old in another, why flints and pebbles are found covered with balani, or 

 why the remains of terrestrial mammalia are associated with those of whales 

 and fishes. 



VOL. V. SECOND SERIES. 3 B 



