32 ME. C. J. GILBERT OX DEPOSITS OF HIGH-LEVEL [vol. lxxv, 



3. On the Occurrence of Extensive Deposits of High-Level 

 Saxds and Graa'els resting upon the Chalk at Little 

 Heath near Berkhamsted. By Charles Jesse Gilbert, 

 F.G.S. (Read January 22nd, 1919.) 



[Plates II & III.] 



'The deposits hereafter described occur at Little Heath, on the 

 north-east side of the valley of the Bulbourne, near Berkhamsted, at 

 550 feet above sea-level and in latitude 51° 45' 45" N. ; longitude 

 0°-31' 30" W. (See D on the map, p. 34.) They rest upon the 

 Chalk of the extensive tableland, which, gradually rising towards 

 the north, culminates at the scarp of the Chiltern Hills. This 

 : scarp hereabouts has an average height of about 700 feet, but 

 rises at the Ivinghoe Beacon to 808 feet. 



The section to which attention is specially directed occurs in a 

 pit that has been recently opened on Little Heath Common by 

 the Hemel Hempstead Corporation, with the permission of Lord 

 Brownlow, for obtaining supplies of road-metal. 



A generalized section of this pit shows the following beds in 

 •descending order : — 



Thickness in feet. 

 6. S iirf ace-soil, with bleached Eeading pebbles... about 2 

 5. Pebbly clay and other glacial deposits, varying from 2 to 20 



4. Stratified loamy sand 5 to 6 



3. Stratified coarse gravel 17 



2. Dark clay, with black-coated unworn flints and small 



well-rounded pebbles 6 inches 



1. Chalk. 



No. 6. Surface-soil, with bleached Heading pebbles. — 

 This appears to be made up of a portion of the underlying beds, 

 which has become disintegrated. 



No. 5. The Glacial deposits. — These are somewhat varied 

 in character. At the top is a pebbly clay, entirely devoid of 

 stratification. The pebbles often exceed the clay in total bulk, 

 and vary usually in size from a pigeon's egg upwards. They are 

 highly waterworn. and appear to have been derived almost exclu- 

 sively from the Reading Beds. They are nearly all bleached on 

 the surface, suggesting that they were exposed for a considerable 

 time before being incorporated in their present matrix. The 

 bleaching usually extends only for a short distance into the pebbles, 

 but in practically all cases the original black interior has become 

 stained or faded. 



In many instances, the characteristic node-rings, due to beach- 

 hammering, have completely disappeared. Sometimes, however, 

 they are more or less preserved, though seldom so clearly as in the 



