1889.J THE DISPLACEMENT OF BEACH-LINES. 61 



Quaternary, Cycle III 

 Extending from 350,000 years before the present time till now. 



1"— 3" The Saharian ,,Stage" with 3 oscillations. 



The limits between the cycles of the curve are not drawn 

 at random. The beginning and close of the first two cycles 

 distinguish themselves by their unusually low degree of ec- 

 centricity. The last arc of the cycle and the first arc of the 

 succeeding one have, together, a duration of about 150,000 

 years, and through all that time the eccentricity is very low T . 

 In these two cycles the greatest mean eccentricity occurs also in 

 the middle of the cycle. 



The Eocene epoch appears to have had 16 oscillations, and 

 should correspond with the first cycle; the Oligocene, Miocene, 

 and Pliocene have, also, together, 16 oscillations, and correspond 

 to the second cycle. The lower Eocene corresponds to the arcs 

 !~6; the middle Eocene to 7—12; and the upper Eocene to 13 

 —16. In the same manner, the Oligocene corresponds to the arcs 

 1'— 7'; the Miocene to 8'— 12'; and the Pliocene to 13'— 16'. 



There is, thus, a certain analogy between the lower and the 

 upper Tertiary epochs. We have 6 divisions which nearly 

 correspond to each other in the following manner: 

 The lower Eocene to the Oligocene; the first-named with 6. the 



last-named with 7 oscillations. 

 The middle Eocene to the Miocene; the first-named with 6, the 



last-named with 5 oscillations. 

 The upper Eocene to the Pliocene; both with 4 oscillations. 



The great transgressions of the sea occur in the middle 

 of the cycles, in the middle Eocene, in the upper Oligocene and 

 the Miocene. The mean value of the eccentricity was greatest 

 ln the middle of the cycles. At the commencement and in the 

 Iast Part of the cycles, when the mean value of the eccentricity 

 was small, the sea retreated far back: e. g. between the Chalk 

 and the Eocene, in the upper Eocene and the Pliocene. 



The thought therefore presents itself, with great reasonatfte- 

 Dess ' th at there is a connection between the cycles in the curve 



