136 PKOF. J. PRESTWICH ON THE RELATION OF THE 



per cent. 



1. Flint-pebbles 50 



2. White quartz-pebbles 15 



3. Subangular fragments of flint 20 



4. Subangular fragments of chert and ragstone 10 



6. Pebbles of Lydian stone &c 5 



100 



A bed of white and yellow sand (Bagshot) underlies the gravel. 



At Coopersale Common (or Gaynes Park), two miles JST.E. of 

 Epping, is another range of hills, from 340 to 360 feet high, on 

 which there is also a capping of AVestleton Shingle composed of 



per cent. 



1. Flint-pebbles 56 



2. White quartz-pebbles 20 



3. Subangular fragments of flint 9 



4. Subangular fragments of white Ragstone 12 



5. Pebbles of Lydian stone &c 3 



100 



imbedded in a matrix of light yellow, loamy, quartzose sand. 



To the south of these, and extending from Buckhurst Hill to 

 Woodford Hill, is a considerable spread of pebbly gravel, 10 feet thick 

 in places, of a character intermediate between the Brentwood and 

 the Westleton Beds, but more analogous to the former. It consists 

 almost entirely of flint-pebbles (Bagshot), with a very few white 

 quartz- and other rock-pebbles imbedded in a variable matrix of 

 sand and clay. The lower part is roughly stratified — the upper 

 passes into an unstratified mass of brown and ferruginous clay 

 with few flint-pebbles. 



Middlesex. — The Drift Beds of the eastern and lower part of 

 the county consist chiefly of Glacial and Post-Glacial gravels ; while 

 the higher hills on the north are capped by the Westleton Shingle. 

 Thus the ridges from Baruet and Barnet Gate (410-460 feet), and 

 from Totteridge to Highwood (400-410 feet), and again at Mill Hill, 

 are capped by a poor gravel of this age, from 2 to 5 feet thick, and 

 composed of 



per cent, 



1. Flint-pebbles 50 



2. White quartz-pebbles 15 



3. Subangular flints, stained white and brown 20 



4. Subangular ragstone and chert 12 



5. Lydian stone &c 3 



100 



in a matrix of quartzose sand and greenish clay. 



The Boulder-clay, at a level of about 100 feet lower, extends 

 from Whetstone to Finchlcy and Muswell Hill. The gravel which 

 underlies it in a pit near Finchley Church is of Glacial origin, and 

 is full of northern debris. That at the old section opposite to 

 the " Bald-faced Stag " has been referred to the Pebbly Gravels ; 



