of Life. 29 



still ascending in the series, we come to the Cretaceous 

 formations represented by 12, 13, and 14. a wonderful 

 change takes place. None of the Oolitic species pass 

 into these formations, and some of the genera, especially 

 of chambered shells ( Cephalopoda) are new. There are 

 no marine passage beds in England sufficiently 

 developed clearly to unite the tiuo series. They were, 

 in fact, separated in their deposition by a long period 

 of time during which our territory generally formed 

 land, and which is therefore unrepresented in the 

 British area by marked marine stratified deposits of 

 dates between Oolitic and Cretaceous times. 



I have selected the above instances, as affording a 

 good type of the kind of phenomena that occur again 

 and again throughout the whole series of our geological 

 formations. After a minute examination, therefore, of 

 the stratigraphical structure of our island, the result is, 

 that geologists are able to recognise and place all the 

 rocks in serial order, so as to show which were formed 

 first and which were formed latest ; and the following 

 is the result of this tabulation, omitting minor details. 



It is a necessary part of the plan of this work to 

 give some account of the range, structure, and fossils 

 of the formations enumerated in the following table, 

 and I shall therefore in succeeding chapters give a brief 

 account of each formation or set of formations, be- 

 ginning with the oldest, so as in some degree to show 

 their general relations to each other, and, as far as I 

 can, to give a description of the physical geography of 

 each prominent geological epoch. 



