28 THE REV. EDWI^f HILL ON THE [Feb. I9I2, 



V. Isolated Masses op Chalk. 



The brick-pits in Little Cornard (15), about 2 miles south of 

 Sudbury, lie on and above the 100-foot contour. They show at 

 the entrance some Thanet Sands. Against these, on a slope which 

 seems to be a bank of a former lateral channel of the ancient river, 

 lies a mass of violently current-bedded sands and gravels. Against 

 these gravels, still farther from the present valley, comes a stretch of 

 grey stoneless clay, now mostly worked away. In this grey clay, 

 at the farther side of the pit, lie several large masses of Chalk. 

 They are very large : one, oval in shape, is not less than 30 feet long, 

 by 10 feet in height. They contain no flints : they appear to be 

 not original Chalk, but remanie Chalk, as are some of the Cromer 

 masses. They lie embedded in the clay, which wraps round them 

 and fills fissures. The clay itself looks as if it may be a mud 

 washed from Boulder Clay. 



The valley is wide and open above, but here is contracted by a 

 spur of the plateau to about a third of its former breadth. These 

 masses lie at the end of the spur. Were they stranded here ? The 

 gravels, against which their enwrapping clay rests, indicate 

 powerful currents at levels 20 to 40 feet above the present valley- 

 floor. 



YI. General Remarks. 



This paper is the fruit of some words from Mr. Harmer, spoken 

 when showing some Norfolk sections. He remarked on the light 

 which might be thrown on the origin of Boulder Clay by the beds 

 that immediately preceded it. I had almost relinquished Glacial 

 studies, but the new idea roused me to a re-examination of West 

 Sufl'olk sections. 



The foregoing descriptions show that close to Sudbury, on each 

 side of the existing Stour Valley, at or just below the level of 

 200 feet O.D., which is 120 feet above the present valley-floor, 

 there are extensive deposits of sands and silts, such as appear to be 

 aqueous deposits, laid down in shallow waters ^ ; and that these pass 

 by a continuous transition into normal Chalky Boulder Clay : also 

 that their undisturbed condition negatives the existence, during 

 that transitional period, of any action such as thrust or drag. 



Again, close to Sudbury, at levels of about 170 feet O.D. and 

 below, on the sloping sides of the valley, are sands and gravels, 

 often very coarse, generally presenting strong current-bedding, such 

 as indicates torrential water-action. These gravels contain trans- 

 ported sheets and blocks of previously-formed Boulder Clay, some 

 of which have shapes such as would be the consequence of slip 

 down slopes. There has been some action able to deposit also, at 

 the same level as some of these gravels. Chalk masses which weigh 

 hundreds of tons. 



It may be noticed that the foregoing deductions, made for the 



1 Compare the suggestion of an extra-G-lacial lake, Proc. Geol. Assoc, vol. xv 

 (1898) p. 454. 



