136 RAMBLES AND REVERIES. 



The tops of almost all the hills around Caterham 

 are capped with gravelly outliers of Tertiary age. 

 It is this feature which explains the luxuriance of 

 the vegetation where we should naturally look for 

 the barrenness of a typical chalk district. A boring 

 at Caterham shows that there the Tertiaries have 

 maintained a thickness of eighty-nine feet, notwith- 

 standing the wearing down which has been going on 

 for centuries. As these Tertiary deposits agree with 

 the chalk in general direction, being shaped into 

 the same synclinals and anticlinals, it is clear that 

 they must have been laid before the final upheaval 

 of the chalk took place, for otherwise they would 

 have filled up the hollows caused previously by 

 denudation of the chalk, while the higher portions 

 of the chalk would have been without the gravels 

 that now cap them. Thus is the eye trained by 

 geological methods to read the history of the 

 landscape in the furrows and markings upon its face. 



Journeying on in a southerly direction, a number 

 of Secondary formations are encountered. These 

 occur one after the other along the line of route in 

 exactly the same order as that in which they are 

 met with when vertical borings are made into the 

 earth's crust. The Caterham boring already referred 

 to reveals as the order of superposition the Tertiary, 

 the Chalk, the Upper Greensand and Gault, and 

 the Lower Greensand. A boring made in Tottenham 

 Court Road in search of water for Meux' Brewery 

 showed the same order, and was continued into the 

 Oolites. 



The most remarkable circumstance in connection 



