Royal Ascot ^ 



appearance, can each be placed In its relative geological 

 division. 



The Bagshot Sands can be divided into three distinct 

 and persistent classes — Lower, Middle, and Upper — severally 

 characterised by peculiar groups of organic remains, and by 

 differences of lithological features. The Lower Bagshot 

 Sands repose conformably on the London Clay. They 

 consist mainly of whitish and light yellow siliceous sand, 

 with a few seams of pebbles and some traces of organic 

 remains, and vary in thickness, from loo to i5o ft. Over- 

 lying the Lower Sands are a few beds of white, yellow, 

 liver and cream-coloured laminated clays, and one or two 

 beds of green sand. Their thickness altogether does not 

 exceed from 40 to 60 ft. ; nevertheless they form a division 

 of persistent range and structure. These clays are most 

 extensively distributed around Addlestone and Chertsey, 

 where they attain a thickness of 10 to 20 ft. Above these 

 clays is a thick stratum of green sand, generally very pure 

 and of a dark bottle-green colour, maintaining a uniform 

 thickness of about 12 to 20 ft. Intercalated with these 

 green sands are occasional layers of large and small rolled 

 flint pebbles, which in some cases are concreted into 

 actual rocks. This division forms an excellent geological 

 horizon, dividing the Lower from the Upper Bagshot 

 Sands. Its presence is indicated by a greater fertility and 

 the general occurrence of watercourses. Incumbent on 

 these green sands is the Upper and main mass of the 

 Bagshot Sands. This division consists of irregular bedded 

 sands of a light yellow colour, occasionally slightly tinged 

 green, red, or ochreous, and is best seen in the ridges of 

 Frimley or Chobham, which are formed entirely of it, 



294 



