GLACIAL BEDS, 503 



basalt, of which blocks measuring over 6 feet in length have sometimes been found ; 

 but huge boulders of Chalk-vvith-flints, one re-deposited mass or rather strip of 

 which was upwards of 180 yards in length. These masses are well seen between 

 East Runton and Sherringham.^ (See Fig. 88.) 



Messrs. Wood and Harmer attribute the formation of the marly portion of the 

 Contorted Drift to a discharge of ground-up Chalk from the dAoiichure of a 

 Glacier that occupied the Chalk country to the west ; the brickearth or stony loam 

 which forms the easterly development of the Contorted Drift being due to a river 

 discharge in that part ; the two sediments intermingling in the intermediate area, 

 and producing the alternations of marl and brickearth there presented by this 

 formation. The detached masses of the marl were, they consider, introduced into 

 the brickearth portion of the deposit by the agency of bergs, which, breaking from 

 the Glacier and grounding, picked up masses of the marl forming over the sea- 

 bottom in that part of the area. These masses the bergs carried out into the area 

 where the brickearth was accumulating, and grounding again, embedded them in 

 the brickearth, and even in the subjacent Till, contorting the beds in the process. 

 From detached portions of this marl, which they have found as far south as 

 Claydon, near Ipswich, and Stanstead, near Lavenham, in Suffolk, they infer that 

 this deposit covered the west of Suffolk and Norfolk, but underwent denudation 

 in the former area during ' Middle Glacial' times, the sands of that age, west and 

 south of Diss, being banked up to bosses of it in some parts, and overlying it in 

 others. In fact, it was the opinion of Messrs. Wood and Harmer that during the 

 interval between these deposits, the valley system of East Anglia was marked out." 

 The contortions have also been attributed partly to the thawing of masses of ice 

 which had been fixed among the beds during their deposition. 



Although the term Contorted Drift is usually confined to the Lower Glacial 

 Beds, yet similar contortions also affect the Chalk and sometimes tlie Norwich 

 Crag ; and there are strong reasons for believing that the disturbances were pro- 

 duced by the agent which formed the Chalky Boulder Clay, a view first suggested 

 by Mr. S. B. J. Skertchly. (See sequel.) 



The Cromer Till may be regarded as the product of an ice-sheet, deriving its 

 shell-fragments from the bed of the sea or from Pre-glacial deposits over which the 

 material was pushed. Submergence following, the succeeding Contorted Drift, 

 which exhibits evidence of stratification and sometimes of ripple-marks, was 

 probably deposited in the sea ; while some of the large blocks of igneous and 

 metamorphic rocks may have been brought by ice-bergs, perhaps from the 

 Scandinavian area. The Middle Glacial sands and gravels succeeded the more 

 muddy sediments, and all these deposits were subsequently acted upon by a force 

 sufficient to produce the violent contortions before mentioned ; but before 

 attempting to explain them, it is desirable to describe these sands and gravels and 

 other overlying Glacial Drifts. 



Inland many large boulders have been taken out of the Lower Boulder Clay, or 

 have been turned up during the ploughing of land in tracts where this formation is 

 uppermost. These have, in numerous instances, been removed to the adjacent 

 village or homestead to serve some useful purpose. 



The Contorted Drift is extensively worked for bricks around Norwich, North 

 Walsham, Aylsham, and many other parts of Norfolk ; it is sometimes called the 

 Norwich Brickearth. In Suffolk it has been observed at Somerleyton, Beccles, 

 Harleston, Woolpit, Boxted, Sudbury, Kesgrave, Hasketon, etc* At Woolpit 

 there is a laminated clay which has been celebrated for the manufacture of white 

 bricks since the time of Queen Elizabeth.* At Diss, and also near Surlingham and 

 Rockland, there are beds of laminated brickearth which have been employed for 

 brickmaking. (See p. 467.) 



The marl beds are worked for lime at Weybourn, Holt, Ileydon (hydraulic 

 cement), and other places. 



1 Wood, G. Mag. 1868, p. 454 ; Reid, G. Mag. 1880, p. 62. 

 ^ G. Mag. 1868, p. 454 ; Q. J. xxxui. 78 ; Q. J. xxxvi. 471. 

 3 G. Mag. 1868, p. 454. 

 * J. H. Blake, Geol. Stowmarket (Geol. Surv.), p. 13. 



