Stather : Quartzite Pebbles on the Yorkshire Wolds. 



of course hig-hly charged with fragments of chalk and flint, but 

 the pebbles in question can be distinguished from this local 

 material at a glance. 



It has not yet been ascertained whether the pebbles occur 

 over the whole of the western parts of the Wolds, but judging 

 from the areas which have already been under observation, the 

 general conditions of their occurrence seem to be as follows : — 



(i) The pebbles occur at high levels,, generally from 400 feet 

 to 500 feet above sea-level, near the western escarpment of the 

 Wolds. 



{2) They are scattered unevenly over the fields, sometimes 

 few and far between, at other times averaging as many as six 

 pebbles to the square foot. 



(3) The pebbles are rare on the sides of the dales, but are 

 the most plentiful on the high-level flat lands which intervene 

 between the dales ; the rule being the flatter the land the more 

 numerous the pebbles. 



(4) They also occur, as the only foreign pebbles, in the Chalk 

 gravels which underlie the boulder clay at Hessle, and they are 

 also recorded from the old Chalk breccias, Fairy Stones, etc., of 

 the higher Wolds. 



In seeking for an explanation of the presence of these 

 scattered pebbles on the high Chalk Wolds, it may be pointed 

 out that (i) no local rocks occur in situ from which the pebbles 

 can have been derived ; that (2) the pebbles, being limited to 

 quartzites and sandstones, cannot liave come from the Glacial 

 Drift to the east of the Wolds, because these drifts are famous 

 for the immense variety of rocks represented amongst their 

 boulders and pebbles ; that (3), for similar reasons, neither can 

 tlie pebbles be correlated with the gravels of the Vale of York. 



In writing some time ago to ask the opinion of my 

 friend, Mr. G. W^. Lamplugh, with regard to these interesting 

 strangers, I received in reply a letter, from which the following" 

 sentences are, with his permission, reproduced : — 



' 1 cannot even ofl'er an opinion as to what your quartzite 

 drift on the lop of the Wolds may be. It may be well, however, 

 to remind you of the ' Lenham Beds' of Pliocene age that 

 c>ccur in scraps on the North Downs. Relics of this kind might 

 persist on the surtace of the Wolds where protected from glacia- 

 tion, even though a considerable thickness of the underlying" 

 Chalk had disappeared in solution. As the result of work in 

 other places >inco loa\"ing Yorkshire, I do not feel so confident 

 that tlie \\\^lds remained ice-free throughout the Glacial period. 



Naturalist, 



