66 BLYTT. THE DISPLACEMENT OF BEACH-LINES. [No. 1. 1889.] 



in each cycle, need not be owing to any very great rise of 

 the sea-level; as great flat-lands may be covered and drained 

 by a relatively small vertical displacement of the beach-line. 

 But those great changes in the distribution of land and sea were, 

 sure enough, sufficiently great to produce considerable changes 

 of climate. Extensive seas in higher latitudes cause their climate 

 to be mild and vice versa. 



If we now compare, keeping these principles in view, the 

 curve of the eccentricity with the geological series of beds, we 

 find an agreement indicating that the hypotheses are correct. 

 The two cycles of the calculated curve correspond to two geolo- 

 gical cycles. Each of the cycles has 16 arcs that correspond 

 to 16 slight oscillations of the beach-lines or 16 geological sta- 

 ges. In each of these stages there are as many alternations of 

 strata as there are precessions in the corresponding arc. And 

 the mean sea-level rises with the mean eccentricity in the mid- 

 dle of the cycles, and falls at the limit between them, and, 

 hand in hand with the mean sea-level, rises and falls, also, the 

 temperature in the higher latitudes. 



The doctrine here discussed agrees with LyeWs great prin- 

 ciple. Slow changes in the length of the winter and summer 

 and in the force of the tidal-wave, produce periodical changes 

 of climate, and displacements of the beach-lines. The Earth 

 changes its form slowly and imperceptibly. The changes take 

 place so slowly that the effects, first, after expiry of many thou- 

 sands of years, begin to appear distinctly. There are two astro- 

 nomical periods which are the causes of the great and radical chan- 

 ges, of which geology bears to us testimonies from far remote 

 ■■iges, and which will still continue in the future, for millions of 

 years, to produce similar changes in the geography of the Globe, 

 its climate, and its animal and vegetable life. 



