THE THAMES EEOM GUILDFOED TO IS^EWETJEY. 43 



high road close to the Gordon Boys' Home (not marked on the 

 map). It is as follows : — 



1. Gravel — Surface-bed of red and green mottled gravel resting irregu- 



larly on — 

 Yellow sand with layers and patches of stones, green sand in places, 

 8 feet. 



2. Yellow sand — Upper Bagshot. 



A sample from one of the layers of stones in bed 1 contained 10*8 

 per cent, in weight of irony concretions from the Upper Bagshot, 

 and Mr. R. S. Herries and the writer found several casts of shells in 

 place in this gravel, all obviously derived from that formation. We 

 could not find any of these casts in the Upper Bagshot, bed 2 in 

 this pit, and there can be little doubt that they come from the 

 higher beds which originally existed between this hill and Chobham 

 Ridges, two miles to the east, such casts being common near the top 

 of the Eidges. 



The pebble-bed which forms the base of the Upper Bagshot crops 

 out near here, and consequently the sheet of gravel at the side of 

 the present stream (Hale Bourne) is very pebbly. There is a pit 

 102 feet above O.D. close to Clapper's Farm, as shown in fig. 3, 

 facing this page. 



Accumulations of sand such as that just described are very 

 common in the Bagshot country and may easily be mistaken for 

 the Bagshot Beds themselves. A very good example near Walton 

 is described by Mr. Hudleston,^ and there is another near Addlestone 

 Station, where the Lower Bagshots are exposed in a cutting bedded 

 horizontally, while at the station-end of the section they are cut off 

 by a sandy drift very irregularly bedded. The best example of 

 this sandy drift which I have seen is in the great sandpit at Chavey 

 Down, where the section is as folio Ws : — 



1. Earth; few stones; a little gravel in places 2ft. 



2. Sandy Drift 4 ft. 6 in. to 8 ft. 



consisting of — 

 a. Irregularly bedded yellow and white sand. 



h. Sand full of blocks of yellow and white sand and bits of clay lying 

 at all angles ; one of these blocks measured 1 ft. 8 in. X 10 in. 



3. Lower Bagshot. Yellow sand with numerous clay laminae, with irony 



concretions ; bedding nearly horizontal, but slightly curved under the 

 Drift at the north-western edge of the pit. 



The sand-bed 2 does not cap the hill, but rests on its north- 

 western face, and its top is about 290 feet above O.D. The blocks 

 of sand contained in it are clearly derived from the Lower Bagshot 

 Beds, and I should say the whole is of Glacial origin, but do not 

 pretend to decide on the exact process of its formation. 



There is a somewhat similar deposit in the Brick and Tile Com- 

 pany's brickyard, north of Bracknell, which I at one time thought 

 was Bagshot Sand, but which Dr. Irving rightly calls gravel.^ I 

 do not, however, follow that author in his views as to the lacustrine 



1 Quart. Journ. Geol. Soc. vol. xHi. (1886) p. 152. 



2 Ibid. vol. xlvi. (1890) p. 562. 



