368 Rev. W. B. Clarke on the Geological Structure 



6. Previously to this diluvial action, and after it, the inland waters of the 

 then dry land bore to the sea, animal and vegetable remains, vestiges of which 

 occur on the Norfolk coast and elsewhere. 



7. The climate of this part of the globe was then different from the 

 present. 



8. After this period, and probably in prolongation of the first great cata- 

 strophe, a series of shocks acting from below shattered the surface, and gra- 

 dually elevated the whole district, including the chalk, till the crag obtained 

 the height of nearly 100 feet above the level of the sea ; and by this movement 

 were produced the valleys or lines of fissures through which the drainage of 

 the county is effected ; and during this operation the beds of gravel were 

 partly accumulated. 



9. No great convulsions have since taken place. 



10. By the action of springs and the constant battering of the sea, the su- 

 perficial contents of the London clay and crag have been reduced several 

 miles, vestiges of their former extent being traceable in rocks and sands nearly 

 always submerged. 



1 1. By the set of the tides, vast accumulations of shingle and sand have 

 been formed at projecting points, protecting, in some places, the cliffs from 

 further destruction ; but at Harwich Bay they have blocked up the ancient 

 estuary, and compelled the Stour and the Orwell to form a new outlet. 



12. The average amount of annual degradation of the coast is about two 

 yards in breadth ; and, in consequence of the conformation of the ridges of 

 crag and London clay, the cliffs will gradually diminish into a low, sandy shore. 

 The period estimated for effecting this destruction is calculated to be another 

 century. 



The following account of wells and sections was obtained by personal ob- 

 servations or from authentic information, and it is given to assist in illus- 

 trating the preceding remarks. The localities are disposed geographically 

 for the sake of comparing the sections nearest each other ; but to enable the 

 reader who may wish to study the structure of the different deposits at all the 

 points mentioned, the accompanying numerical lists, arranged under each 

 formation, are added. 



Diluvium, Nos. 2, 3, 6, 8 to 12, 14, 15, 18 to 37, 39 to 50, 52 to 54, 58, 

 60 to 64, 66 ? 67 to 71, 73, 74, 76 to 82, 87, 88, 93 to 96. 



Crag, Nos. 5, 10, 13, 50 ? 81 to 87, 90 to 95. 



London Clay, Nos. 1 to 7, 9 to 14, 17, 50? 51 ? 55, 56, 57, 65, 72, 80, 86, 

 89. 90, 92, 95, 97. 



