448 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



5 and 6. Thus, for instance, on the Cromer coast, we find the for- 

 mer most deeply and irregularly indented by troughs filled with the 

 base of 5, both deposits being there in much greater thickness than 

 in the case before us ; while in the inland sections we find it rising 

 through 5 in bosses of greater or less extent, the Boulder-clay (6) 

 being spread there over it and over 5, sometimes resting on the one 

 and sometimes on the other, thus showing 4 to have formed either 

 islands or shoals in the Middle Glacial sea. 



The intraglacial denudation of the Tare valley, disclosed by the 

 sewer-works, serves to explain a feature brought before the Society 

 by one of us in 1866*. In that case a bed of Boulder-clay was 

 shown lying in the bottom of the Yare valley, and described as a third 

 Boulder-clay. Although, at the time, we both regarded it as distinct 

 from the great Boulder-clay (6), we now incline to think that the bed 

 in question is either the bed a, or else merely the Boulder-clay 6 

 brought down into the bottom of the valley by a repetition of the denu- 

 dation which, we have just seen, commenced after the deposit of the 

 contorted drift 4. The dotted lines in our section represent probably 

 the way in which 5 bent down into this hollow of denudation ; and 

 it seems to us that the denudation was renewed after the deposit of 

 5, sweeping out so much of that bed as had been deposited in the 

 hollow, but leaving it in the hole or trough which is shown in our 

 section, and thus allowing 6 to be thrown down upon the chalk di- 

 rect, as shown in the section referred tof. 



In the adjoining valley of the Wensum a somewhat similar state of 

 things has occurred, as we have found there the Middle Glacial sand 

 (5) overlain by the Boulder-clay (6) in a hole in the chalk, and 

 resting directly upon it, below the level of bed 3, which, in that part, 

 forms the general base of the formations superior to the chalk, and 

 constituting the sohd mass of the country. 



No infiltration or slipping can explain these features, because the 

 blue clay {a of the accompanying section) is not, so far as any of 

 the pits around disclose, present in the neighbourhood, and because 

 the deposits which underlie the beds in question, when in their 

 usual position, do not occur beneath them when thus abnormally 

 placed, although, in the case of the blue clay a, we ought to add 

 that the shafts do not reach its base, so that it is unknown whether 

 anything intervenes between it and the chalk. 



. In conclusion, we would venture to remark that the sections re- 

 ferred to appear to us to militate against the excavation of our 

 East-Anglian valleys by river-agency, as well as to show the il- 

 lusory character of the level-test as applied to the elucidation of 

 the age of the newer Tertiaries, especially of those occurring in 

 valleys ; although we are far from saying that the evidence of level, 

 when kept in due subordination to other features, has not its value. 



Note. — This paper was postponed in the hope that the progress 

 of the works would have brought further facts to light ; but nothing 



* Quart. Journ. Geol. Soc. vol. xxiii. p. 89. 



t Ibid. See the bed a of that section, which is not to be confounded with 

 the bed a of the section which accompanies the present paper. 



