WESTLETON BEDS TO THOSE OF NORFOLK, ETC. 137 



I should have placed it also with the same Glacial Beds ; but my 

 notes are insufficient. 



The Westleton Beds are difficult to follow in this direction. 

 They do not seem to rise so high as further north. Some beds 

 at Hendon (280 feet) may possibly be referred to them, as also 

 a small outlier which caps the hill (278 feet) at Horsington, two 

 miles south of Harrow. This isolated patch, which is a mere 

 remnant scattered on the surface, consists of 



per cent. 



1. Flint-pebbles 42 



2. White quartz-pebbles 10 



3. Stibangular flints stained brown 30 



4. Subangular chert and ragstone 18 



100 



With respect to Highgate and Hampstead Hills, which rise 

 to the height 412 feet, I hesitate how to class them. I have 

 found some fragments of worn cherty ragstone and a few rare 

 quartz-pebbles on Hampstead HiU, with abundant flint-pebbles of 

 local (Bagshot) origin ; but the characters are not sufficiently 

 marked to satisfy me. They may be Westleton or they may be 

 outliers of the Southern Drift. 



In the north of the county, a well-marked Westleton outlier may 

 be seen in the wood (400 ft.?) 1^ mile north of South Mimms, 

 consisting of: — 



per cent. 



1. Flint-pebbles 38 



2. White quartz -pebbles 28 



3. Subangular flints, not stained 24 



4. Subaugular chert &c 



5. Pebbles of white quartzite, Lydiau stone, &c 4 



100 



The adjacent ridge, extending from Potter's Bar to Bell Bar (380 

 to 400 ft.), is also capped by a thin bed of Westleton Shingle, but 

 there were no sections open at the time of my visits. 



The Pebble-Beds of Stanmore, Elstree, and some adjacent hills 

 belong to the Brentwood group. 



Hei^tfordshire. — The London-Clay hills of the north of Middlesex, 

 capped by Westleton Shingle, are continued into Hertfordshire, 

 where they form, between Hatfield and Hertford Heath, a con- 

 spicuous range from 320 to 380 ft. high, and overlooking, at a 

 level of from 180 to 240 ft. lower, the broad valley of the Lea and 

 Mimram, over which are spread (jlacial gravels and sands, covered in 

 places by the Boulder-clay. The material difference of level and 

 the marked character of the beds here bring out very clearly the 

 discordant relation of these Glacial and Pre-Glacial Beds, as shown 

 in the following section (fig. 11) : — 



l2 



