and Freshisater Deposits of Eastern Norfolk. 375 



name of Black Meg. This collection extends about two 

 miles, chiefly opposite to Beeston Hill*. 



The author just cited truly remarks, that this singular as- 

 semblage of boulders must have been dislodged from the 

 wasting cliffs, of which the softer and finer materials have 

 been removed by currents, for similar boulders are occasion- 

 ally observed in the midst of the clay or till of the cliffs. 



In different parts of the interior of Norfolk, boulders weigh- 

 ing several tons have been found in blue clay or tillf. 



I stated in the first edition of my Principles of Geology 

 that I was unable in 1829 to draw a line of demarcation be- 

 tween the crag and the drift or diluvium. The Rev. W. B. 

 Clarke afterwards insisted on the distinctness of the two for- 

 mations J, in which opinion I now concur, although I am 

 still unable, in many spots, as, for example, near Weybourne, 

 and between Southwold and Yarmouth, to say where the crag 

 ends and the stratified drift begins. But this difficulty arises 

 from the absence of fossils in the crag as well as the drift, and 

 from the fact that the strata in the latter are often as regular 

 and continuous for considerable distances as those of the 

 crag. 



Professor Sedgwick informs me, that in the unstratified 

 brown clay or till of certain parts of Cambridgeshire, large 

 angular blocks of lower green sand and chalk, with fossils of 

 the Oxford clay and lias, occur. The till alluded to attains 

 at some points a thickness of 300 feet: it resembles that in the 

 Norfolk mud cliffs, and has been traced over many of the ad- 

 joining counties. Its extent therefore in area and depth ren- 

 der its history of high importance in the geology of the east 

 of England. 



I mentioned in the beginning of this paper, that I recog- 

 nized the strongest resemblance between the boulder forma- 

 tion which I have seen in Sweden, Denmark, Holstein, and 

 other countries, and the drift of Norfolk ; and as I believe 

 coast-ice and icebergs to have been instrumental in trans- 

 porting much of the large and small detritus in Scandinavia, 

 so I presume that at the same period the effects of the same 

 agency was extended to the British seas, although on a 

 smaller scale. But while some of the Norfolk erratics may 

 be of northern origin, other portions of the associated drift 

 may have been brought from neighbouring regions, and per- 

 haps in an opposite direction, just as we now observe that 



* Geology of East Norfolk, p. 24, 1827- 



fC. B. Rose, Geology of West Norfolk, Lond. and Edin. Phil. Mag , 

 January 1836, p, 195. 



% Geol. Trans., 2nd Series, vol. v., part 2, p. 363. 



