XVII.] GEOLOGY OF THE THAMES BASIN. 



275 



the surface of the Thames basin ; though strata of a similar 

 character appear at the surface, further to the west. All the 

 different strata which thus make up the floor of the Thames 

 basin contain fossil remains of animals or of plants, or of 

 both, sometimes in great abundance. 



Such is a broad and general statement of the facts which 

 have been ascertained respecting the structure of the floor of 

 the basin of the Thames. How are they to be interpreted ? 

 Some light may be thrown upon this question by considering 

 the method which is pursued by antiquaries and archaeo- 

 logists, in order to extract trustworthy history from the works 

 of men. 



i Jvvig^y^^^l-^'lX- 



o 



=IFEET 



Fig. 80. — Section exposed in Cannon Street, London, iZ^i. 



In 185 1, during some improvements which were being 

 made in Cannon Street, in the city of London, a deep 

 digging exposed a section such as is represented in Fig. 80.^ 

 At some distance below the level of the street. A, an old 

 pavement, B, was found ; while, deeper than this, and 

 separated from it by a considerable quantity of soil, C, 



1 This section was recorded at the time by Mr. Chaffers. See his 

 Marks and Monograms on Pottery, 



T 2 



