Horace B. Woodurird—The Chalky BouMer-clay. 495 



the great Chalk boulders, belong to the period of the greatest glacia- 

 tion, or of the Chalky Boulder-clay.^ My own observations in 

 Norfolk coincide, as the disturbed Chalk at Trowse was clearly 

 connected with the Chalky Boulder-clay ; so also were sundry 

 remarkable disturbances in the Chalk near Wells. ^ 



The long-disputed Boulder of Chalk at Eoslyn Hole, Ely, is in 

 direct association with the Chalky Boulder-clay ; so also is the large 

 tract of Chalk and rearranged Chalk discovered at Catworth by 

 Mr. Cameron.^ Again, the well-known masses of Lincolnshire 

 Limestone that occur in the Drift at Great Ponton, as first observed 

 by Professor Morris, are associated with the Chalky Boulder-clay, 

 occurring in these and other cases at or near the base of the Drift. 



A large transported mass of Marlstone, more than 200 yards 

 across, was found by Professor Judd capping Beacon Hill, south 

 of Swayfield. He remarks : " It is noteworthy that these masses 

 always belong to the rocks which form the highest ground," and 

 that " Some of the masses of the Marlstone Eock-bed have been 

 carried across deep valleys, a distance of probably not less than 

 30 miles." He then attributed their transportation to floating-ice.* 



More recently Mr. Fox-Strangways has observed "a mass of 

 Lincolnshire Oolite, at least 300 yards long and 100 yards broad," 

 to the north-west of Melton Mowbray,^ and also a mass of Marl- 

 stone, 12 feet across, near Dunton Basset.^ These also were included 

 in the Chalky Boulder-clay. 



Far west again, in the elevated region of the South Wales Coal- 

 field, a transported mass of Carboniferous sandstone upwards of 

 200 yards in length has been discovered by Mr. W. Gibson. 

 " Though its bedding is only slightly disturbed, yet the whole mass 

 has been ascertained to lie upon Boulder-clay, and must therefore be 

 regarded as a huge boulder." "^ It is interesting to note that Chalk- 

 flints have been found in the Drift of this region ; and, although we 

 have no positive evidence to assert that it is of the same age as the 

 Chalky Boulder-clay of the Midland and Eastern Counties, yet we 

 may well believe that it belongs to the period of maximum glaciation. 



Looking to the source of the larger cakes of Cretaceous and 

 Jurassic rocks, we find that they occur in areas where the formations 

 from which they were detached suffered marked denudation. As 

 previously mentioned, the Chalk areas along the Fenland borders 

 had been planed down, and it will be noticed that there is a singular 

 absence of Jurassic outliers along the western margin of the great 

 Lincolnshire "Cliff," and this absence may reasonably be attributed 

 to their removal during the Glacial period. 



^ "Geology of Cromer," pp. 111-117. 



2 Quart. Journ. Geol. Soc, vol. xxxv, p. 106 (Proc.) ; " Geology of Norwich," 

 p. 135; " Geology of Fakenliam," etc., p. 22. 

 ^ Proc. Geol. Assoc, vol. xiii, p. 356. 

 * " Geology of Rutland," etc., pp. 246-7. 



5 Report of Director-General of GeoL Survey for 1892, p. 249. 



6 Geol. Mag. 1897, p. 57. 



'' Report of Director- General of Geol. Survey for 1894, p. 275. 



