20 HAMPSTEAD HILL. 



and vcf^etable growth upon the character of the ground beneath 

 the surface. How useful it would be if the German custom 

 of taking the pupils of schools out to see and study instructive 

 localities were followed in England. Not only would it be 

 immediately instructive, but it would promote habits of 

 observation of general educational value, antl, at the same 

 time, greatly interest and delight the pupils, diversify, and 

 make more attractive their school life, and thereby give them 

 greater zest and energy for their general work and study. 



But, although Hampstead is highly interesting and instruc- 

 tive, the structure of the hill is very simple, since the whole 

 consists of only two great beds of material called " Formations," 

 one lying on the other almost horizontally. The lower one, 

 which forms the great bulk of the hill, is an immense mass of 

 clay, and the upper one, which forms the heath-covered summit, 

 consists of sands ; thus the whole hill is made up of clay and 

 sand. 



The former of these two great beds, the clay, is part of 

 the main mass of the formation called the " London Clay," 

 which extends eastwards from Hungerford, in Berkshire, to 

 the sea-coast at Harwich, and constitutes by far the greater part 

 of the extensive area formed by the two counties of Middlesex 

 and Essex. The other and upper of the two great beds, the 

 sand, is, on the other hand, a detached and outlying portion 

 of the formation called the '* Bagshot Sands," the main mass 

 of which, as the name indicates, occupies the district around 

 Bagshot in Surrey, and forms the extensive barren heaths and 

 commons about that place, Woking, Aldershot, Frimley, and 

 Sandhurst, but not extending uninterruptedly further eastwards 

 than Chertsey and Weybridge. 



The London Clay forms the whole of the ground of Hamp- 

 stead up to about 360 feet above sea-level, and supports the 



