Horace B. Woodtvard — The Chalky Boulder-clay. 493 



Drift " of Murchison.i This Drift occurs here and there over 

 a wide area in Warwickshii'e, and may be a result of the denudation 

 of Boulder-clay. 



During the progress of the Geological Survey in Norfolk and 

 Suffolk, numerous instances of contortion in the strata underlying 

 the Chalky Boulder-clay, and occasionally of intrusive tongues of 

 that material, were noticed.- Chalk and Crag were in places dis- 

 turbed, but the marked contortions were usually to be found where 

 brickearth or clay, or thin alternating clays and sands, lay beneath 

 the Boulder-clay. (See Fig. 2.) Where glacial muds, formed during 

 temporary recession of the ice, were afterwards overridden, erosion 

 without marked contortion was sometimes to be seen. (See Fig. 3.) 



Fig. 3. — Pit one-quarter of a mile nortli-west of Dove Inn, Poringland, Norfolk. 



5 Fi^"TMTf!Tgi^^ 



5. Soil and decalcified Boulder-clay, 2 or 3 feet. 



4. Chalky Boulder-clay. \ „ 7 f + 



3. Chalky sand (base of Boulder-clay). } ^ O'' ' ^^et. 



2. Yello\vish laminated clays and bands of marl, 6 feet. 



1. Chalky Boulder-clay. 



Thick beds of yielding sand are, as a rule, but little, if at all, 

 disturbed, as may be observed in the well-known coast at Kessing- 

 land, and again where the Boulder-clay rests on the remarkably 

 false-bedded Lower Greensand at Grove Bury, near Leighton 

 Buzzard. At the last-named locality, where the sections were noted 

 by Mr. A. C. G. Cameron,^ portions of the sand have been torn 

 away and incorporated with the Boulder-clay, but the main mass 

 of the Lower Greensand is wholly undisturbed. Sands which 

 had been frozen to the base of the ice-sheet may have been so 

 removed, but in their severance from the main mass of underlying 

 sand no disturbance was therein produced. 



Intruded masses of Chalky Boulder-clay have been noticed, not 

 onlj' beneath uptilted Chalk, but in the midst of soft gravels and 



^ Quart. Journ. Geol. Soc, vol. xxvi, pp. 205-6. See also paper on Gravels 

 by H. J. Osborne White : Proc. Geol. Assoc, vol. xv, p. 157. 



^ "Geology of Stowmarket," by W. Whitaker and others, p. 9 ; "Geology of 

 Bury St. Edmunds and Newmarket," by F. J. Bennett and J. H. Blake, p. 11 ; 

 " Geology of Norwich," by H. B. Woodward, p. 112. 



^ See Ann. Eeport of Director- General of Geol. Survey for 1896, p. 79. 



