Geology and Paleontology. 167 
beach-lines come to oscillate up and down once, for each rise and 
fall of the eccentricity of the earth's orbit. That is the case in re- 
spect of both the respective arcs of the curve and of the cycles. 
On such a cycle *'the mean level of the sea " rises and falls once 
The sidereal day has (cfr. Damine) become several hours longer. 
It is therefore probable that there must have accumulated such a 
strain in the mass of earth, that a slight increase of strain would be 
sufficient to cause changes of form at the weakest points. It is also 
likely that those partial changes in the solid mass of the earth must 
occur, especially at times of great eccentricity, or some time after 
such an occurrence, when the motive force increases quickest. 
The change in the tidal-wave, caused by the variation of the 
eccentricity, is presumed to be sufficiently great to explain the dis- 
placement of the beach-lines. A few metres of vertical displacement 
of the beach-line is sufficient to produce in the deep basins, an 
alteration of many metres of thick marine and fresh water beds. 
And as regards the changes in the solid body of the Earth, we must 
recollect that the series of beds is not complete at any single spot. 
In other words the oscillations were not general to such an extent 
that they were contemporaneous everywhere. Only by partial 
changes of form sometimes here, sometimes there, always at the 
weakest point in each age, has the solid earth approached to the 
spheriform. To each arc of the curve there corresponds, therefore, 
only a partial and not a general change in the form of the solid 
earth. And the oscillation of the beach-line, corresponding to the 
arc, can, therefore, not be pointed out everywhere, but only in the 
basins when the forces at that time exerted their effect. In this way 
we can obtain a perfect profile only by combining layers of all the 
Tertiary basins. Neither were the changes of the solid earth 
everywhere equal in extent, but were greatest at the weakest points of 
its surface, so that quite extensive local upheavals may be caused 
by slight changes in the length of the sidereal day. 
That is the case as regards the individual oscillations, but even 
the great trangressions of the sea, of which one occurs in each cycle, 
need not be owing to any 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 these great changes in the 
distribution of land and sea were undoubtedly 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 geological cycles. 
Each of the cycles has i6 arcs that correspond to i6 slight oscilla- 
tions of the beach-lines or i6 geological stages. In each of these 
stages there a-e as many alternations of strata as there are preces- 
