1889.] THE DISPLACEMENT OF BEACH-LINES. 59 



we have seen, above, that the same author states that there 

 have been epochs in the Earth's history when volcanicity was 

 far stronger, and wider distributed than at other epochs. We 

 have seen how the upheavals of the land were accompanied by 

 volcanic eruptions, and as regards the Tertiary period, at any 

 rate, it appears as if the great transgressions of the sea were 

 followed by periods in which the solid land began to rise during 

 violent and widely distributed volcanic eruptions. 



In order to aid in the survey, we will, finally, name all the 

 arcs of the curve and the geological stages supposed to corre- 

 spond to them. We will, to some extent, adopt the designations 

 that Charles Mayer-Eymar* has given them. 



Lower Eocene, arcs 1—6. 

 Extending from 3,250,000 till 2.720,000 years before the 

 present time. 



Arc l. The Montian Stage? 



„ 2. The Heersian Stage. 



» 3. The Suessonian Stage. 



„ 4. The Lower Ypresian Stage? \ 



n 5. The Upper Ypresian Stage? ) 



n 0. The Paniselian Stage. 



