52 MR. H. W. MONCKTON ON THE 



Dr. Irving, in his numerous papers, seems very anxious to prove 

 an overlap of the Upper and Middle Bagshot Beds over the Lower 

 Bagshot. At one time he suggested an overlap on to the London 

 Clay, but, with the exception perhaps of Wokingham, he appears to 

 have abandoned this contention so far as the Bagshot country is 

 concerned. 



The result of long-continued and careful investigation is that I 

 am unable to find any existence in the Bagshpt country of the 

 overlap of either the Upper Bagshot Beds or of the Middle Bagshot 

 Beds, but I am inclined to think that there are considerable varia- 

 tions in the thickness of the Lower Bagshot Beds, and to a certain 

 extent also of the Middle Bagshot Beds. 



Li Dr. Irving's 1887 paper,^ he criticizes the method which 

 Mr. E. S. Herries and myself had adopted in 1886,^ saying that 

 underlying our method was the assumption that mere contiguity or 

 proximity to the London Clay is evidence of Lower Bagshot 

 horizons ; but this can hardly be deemed quite correct. Our 

 process consisted in taking admitted sections as types and com- 

 paring those in dispute with them. We found good sections of the 

 junction between the Middle and Lower beds at Goldsworthy Hill 

 and at St. Ann's Hill which are still open and in good order. The 

 finest Lower Bagshot sections now open are, however, those in the 

 railway-cutting and the sandpits at Hedan Hill, Aldershot. In 

 1885 Dr. Irving had claimed them as Upper Bagshot, so that we 

 were unable to refer to them as typical sections, but the evidence 

 for their Lower Bagshot age is now so overwhelming that I find 

 them at my service for that purpose.^ 



Three and a half miles to the north-east of Eedan Hill, on the 

 same line of railway, there are the finest sections in the country of 

 Upper Bagshot Sand at and near Tunnel Hill, so that here we have 

 two sets of excellent type-sections with which to compare those in 

 question. Now, at first sight both the Redan Hill and the Tunnel 

 Hill sections look like yellow sand — indeed so much alike are they 

 that, as before said. Dr. Irving mistook that at Eedan Hill for 

 Upper Bagshot. But on careful examination it is seen that there 

 are differences. Thus at Tunnel Hill (Upper Bagshot) there is 

 little sign of stratification excepting in broad fairly even bands of 

 variously-tinted. sand, there is no false- or current-bedding nor any 

 laminae of clay, and there is an abundance of irony concretions 

 which in places are casts or have impressions of shells. At Eedan 

 Hill and the adjoining pits (Lower Bagshot) there is much false- or 

 current-bedding, clay laminae are abundant in many places, and no 

 cast of a shell has yet been found, though irony concretions are not 

 uncommon. 



In my experience and in that of Mr. E. S. Herries these charac- 

 teristics are wonderfully persistent, and though they may not be 

 infallible I should have the greatest hesitation in classing a false- 

 bedded sand with pipeclay laminae as Upper Bagshot, or in calling a 



1 Quart, Journ. Geol. Soc. vol. xliii. p. 374. ^ Ibid. vol. xlii. p. 402. 



^ Ibid. p. 410 ; ibid. vol. xliii. p. 431. 



