ON THE MOVEMENTS OF THE EARTh's CRUST. 365 



any rate, it appears that the great overflows of tlie sea were followed 

 by periods dm ing wliich the solid ground began to rise during violent 

 ; and wide spread volcanic eruptions. 



For easy reference we will finally enumerate all the arcs in the curve, 

 and name the geological stages suj^posed to correspond to them. To 

 some extent we adopt the names given by Charles Mayer Eymar.* 



LOWER TERTIARY ; EOCENE— Cycle 1. 1 

 Loioer Eocene. Arcs 1 to 6. 



From 3,250,000 years to 2,720,000 years before the present time. 



Arc 1. Etage Montien ? 



2. Etage Heersien. 



3. Etage Suessonieu. 



4. Etage Ypresien inferieur ? >_ ,, . 



t- „,",/,. , . , vLondniien. 



5. Etage Ypresien superieur ? ( 



6. Etage Paniselien. 



Middle Eocene. 



From 2,720,000 to 2,150,000 years before the present time. 

 Arcs 7-12. Etage Parisien, with six oscillations. 



Upper Eocene. 

 From 2,150,000 to 1,810,000 years before the present time. 

 Arcs 13-lG. Etage Bartonien, with four oscillations. 



UPPER TERTIARY.— Cycle 114 



OUgocene. 



From 1,810,000 to 1,100,000 years before the present time. 



Arcs l'-4'. Etage Ligurien, with four oscillations. 

 ^ 5'-7'. Etage Tongrien, with five oscillations. 



* See his valuable " Classification des Terrains Tertiares " (Zurich, 1884). He di- 

 vides his stages into two sub-stages, — one with " niers aniples," and one with " niers 

 basses." Some of his stages however represent several oscillations. He thinks tliat 

 the precession of the ecjuinoxes is the cause of the changes in the level of the sea. 

 The whole of the Tertiary and Quaternary periods must (according to him) have had 

 a duration of only a little over 300,000 years. He founds his views upon Schmick's 

 untenable hypothesis of the dependence of the sea-level upon the precessions. 



t The upper line of curves in the diagram. 



{ The middle line of curves in the diagram. 



