80 GEOLOGICAL POSITIONS. 



3. The actions of the waves upon a sea coast is unceasing-, and the 

 effects of this action are more or less visible on, every shore, according 

 to the consistency of the rocks which compose it. 



4. From the very first moment that the chalk became dry land, this 

 unceasing agent must have operated as it still does, upon such portions 

 of it as extended to the level of the sea. 



5. From that time to the present, is the exact age of the chalk, as 

 a dry land. 



6. The chalk is never superficially level, but is, on the contrary, 

 invariably of a rounded and sloping surface. 



7. The surface of the chalk is always grooved out into valleys, divided 

 hy ridges of various degrees of steepness, hut invariably smooth. 



8. These valleys seldom contain water, or running streams ; they, 

 consequently, have never been altered in their surface by the erosion of 

 rivers, since they became valleys. 



9. Notwithstanding this ahsence of rivers, the chalk valleys univer- 

 sally open either into larger valleys which lead to the level of the sea, 

 or they individually point to this exact level, thus plainly bespeaking 

 the action of waters. 



10. As all chalk valleys, unaffected by the corroding action of the 

 waves, have this character and tendency, we are certain that all other 

 valleys, though now cut short by precipitous sea cliffs, had, originally, 

 the exact same form and tendency. 



11. Our present chalk cliffs are constantly encroaching upon the 

 lands, hy a progress more or less rapid, according to circumstances. 



12. As rotundity is a universal characteristic of the chalk, and as the 

 cliffs will thus all be higher, and further back a thousand years hence, 

 than they now are, it follows that they were more in advance, and con- 

 sequently lower, a thousand years ago. 



, 13. Having the perpendicular of the cliffs, and the angle formed by 

 the hypothenuse with that perpendicular, we can have no difficulty in 

 correctly ascertaining the length of the base. 



14. The length of the base is the exact amount, of space de- 

 stroyed by the action of the waves, since the chalk first became dry 

 land. 



15. The length of the base being ascertained, and also the rate of 

 decay per annum, we are led with certainty to the number of years 

 which have elapsed since the erosive action first commenced. 



16. As this action is unceasing, and as the chalk is peculiarly 



