Correspondence — Mr. Alfred Harker All 



and predecessor, Professor Phillips, the Drift beds of the neighbour- 

 hood of Oxford and the Thames Valley. Beyond the fact of the 

 occurrence of flints in the Thames Valley, he was not aware of the 

 widespread distribution of chert from the Lower Greensand on the 

 higher hills of the Thames district, on which I mainly based my 

 hypothesis of the Southern Drift. In fact, at that time, no one had 

 recoguised this chert debris, or if it had been noticed the fragments 

 were spoken of as Snrsen-stones. 



So far back as 1847, in "The Ground Beneath Us," after speaking 

 of the flint gravel of the Thames Valley, I say : " It must have 

 been from some distant spot that the materials of this gravel had 



been derived The nearest place .... is in the range of 



hills passing by Croydon and Epsom, a distance of six to ten miles 

 southward from Clapham." Again, " Whatever may have been the 

 cause of this exceptional phenomenon the great and preponderating 

 mass of flint debris from the Chalk hills, and of sandstone and chert 

 from the Greensand hills of Surrey, leaves no reasonable doubt that 

 the main bulk of the gravel of Clapham and of London has been 

 derived and transported from the Surrey downs and Sussex hills." 



Mr. Shrubsole sees a difficulty in the existence of a Wealden 

 dome, which he considers open to question. But how, without 

 higher ground than any in the Thames Valley, could debris from 

 the Lower Greensands have drifted over the ground to the north- 

 ward of it? 



These remarks are not intended to convey any disparagement of 

 Professor Phillips' excellent work, which I have often had occasion 

 to study with advantage. Joseph Prestwich. 



BOULDEES OF EL^OLITE-STENITE IN EAST YORKSHIRE. 



Sir, — The absence of the well-known elceolite-syenite (laurdalite 

 of Brogger) from the Norwegian boulders hitherto identified in 

 Holderness has more than once been mentioned, and is cited by 

 Sir Henry Howorth in your August Number as in some way 

 supporting his theory that the boulders were brought artificially as 

 ballast. Why laurdalite should be less suitable for ballast than 

 laurvikite does not appear. The non-recognition of the former is, 

 of course, easily explained by its resemblance to the latter, which 

 occupies a much larger area in the Christiania basin, and is corre- 

 spondingly more plentiful among the boulders. Nevertheless it is 

 satisfactory to be able to record the occurrence of the Norwegian 

 elfeolite-syenite on the Holderness coast. Visiting Dimlington a 

 few months ago, I selected from the profusion of sj^enitic boulders 

 on the beach eight which seemed worthy of closer study. These 

 and the slices cut from them are now before me. Two contain 

 abundant elasolite, and are identical in every respect with specimens 

 of laurdalite from its original home ; one or two others have 

 accessory elgeolite and sodalite. 



Since these boulders were collected on the beach, the facts 

 mentioned do not appeal to those who find comfort in the ballast 

 theory. Indeed, it is not easy to see bow Sir Henry Howorth can 



