42 



A. BLYTT. 



accurate, to be safely used as the base of geological specula- 

 tions, and that the deformations of the curve, owing to error in 

 the values of the masses used by StockweU, are not likely to be 

 considerable 



4. The mean value of the eccentricity is least at the limit 

 between two cycles; it rises in the first and falls in the last 

 portion of each cycle, and attains, thus, its greatest value at 

 about the middle of the cycles. The value for the first and se- 

 cond of the calculated cycles and their divisions is, therefore, 

 as follows: 



Cycle I -r- 3,250,000 — 2,720,000 years . . 0.0304 

 ~ 2,720,000 — 2,150,000 — . . 0.0332 

 ~ 2.150,000 — 1,810,000 — . . 0.0203 

 Cycle II -f- 1,810.000 — 1,250,000 - . . 0.0247 

 -J- 1,250.000 — 700,000 — . . 0.0340 

 700,000 — 350,000 — . . 0.0280 

 Cycle III 350,000 — modern days . . 0.0291 

 As now, therefore, according to our hypothesis, the level of 

 the sea in higher latitudes will rise and fall with the eccentri- 

 ' city, it must, then, not only rise and fall for each arc in the 

 curve, but „the mean sea-level" for long periods must also rise 

 and fall with the mean value of the eccentricity, and cycles 

 like I and II ought therefore to correspond to two cycles in the 

 geological series of beds. The limits between the cycles of 

 the curve ought to correspond to the periods of denudation that 

 separate the geological cycles, and the middle ought to corre- 

 spond to the periods of transgression. 



The correctness of the two hypotheses presented in my Me- 

 moir on Alternation of strata may, as already there stated, be 

 tested, if the geological profiles are compared with the curve <»f 

 the eccentricity of the terrestrial orbit. A first attempt was 

 made at that time with the Upper Eocene and Oligocene layers 

 of the Paris Basin. 



