CI vTION OF WATER-FORMED ROCKS. 77 



ilk ill the north, in Yorkshire; and 



ind and Chalk in the south-west of 

 England. 



sical break in this coun- 

 try tili that between the chalk and the tertiary 

 which i> partly bridged in Belgium, and 



\ rth Amer 



ind surfaces in 

 1 i> eviden remarkable 



sits, . I then a 

 ta . I . gland, 

 iry period. The mani- 

 l in which the Brit- 

 much • than 

 . many of which 

 tly due to the way in which life i> dis- 

 tributed in - th. Therefore 



rm principle in distinguish- 

 LCh other by their : 

 attention has i the difi 



/ which 



gland the principal changes in marine 

 life Silurian and Devonian 



gh the changes in t; life appear 



int. 



mary and Seconda: 

 there is a great change in both the marine and 

 terrestrial lii 



\een the Oolites and C: 16 rocks 



mtly an important change in the 

 terrestrial life, though the change in the marine 

 life is less marked. 



14) The gap in the marine succession between 

 the Secondary and Tertiary is very striking; but the 

 gap in the terrestrial plant life appears to be small. 



