ON THE MOVEMENTS OF THE EARTh's CRUST. i563 



also represents six oscillations. In Transylvania it commences (accord- 

 ing to Koch in Foldtaid Kozlonij, 1883, pp. 118 etscq.) with alternations 

 of clay and marl, npon which follow alternations of gypsnm and marl 

 ('* lower gypsum horizon," first oscillation). Above it, marine deposits, 

 the Perforata-beds — from below u[)waids — {a) an oyster-bed, (,j) argilla- 

 ceous marl (y) calcareous marl (" lower striata horizon"), (')) a shell-bed 

 (''lower perforata horizon"), (s) clay (" upper striata horizon," second 

 oscillation ?), {^) clay with a few hard marly beds and the same fossils 

 as in ,j, (//) another oystei'-bed, {0) clay with oysters, (;) calcareous marl 

 (" upper perforata horizon," third oscillation ? ); above this the Ostrea- 

 c/aj/, a thick clay with oysters and marly beds, and with a sandy calca- 

 reous bed in the middle (fourth oscillation). Over this again the Lower 

 Coarse limestone, generally in two thick beds (fifth oscillation), covered 

 by a thick bed of clay varied with layers of sand, probably a fresh-water 

 formation,* and covered by fresh-water limestone. Finally, the last 

 (sixth) oscillation, the Upper Gypsum horizon, gypsum alternating with 

 clay ; and above it coarse limestone alternating with gypsum ; in other 

 places, clay with Foraminifera (marine), — the Upper Coarse limestone. I 

 have cited all of these details in order to show that these beds, which 

 are all contemporaneous with the " Calcaire grossier" of Paris, seem to 

 indicate six oscillations. 



Above the "Calcaire grossier" the Upper Eocene commences with 

 the continuous series of the Paris basin, which has already' been de- 

 scribed. 



The Lower and Middle Eocene therefore appear to include twelve 

 oscillations, six of which pertain to each of the two divfsious of the 

 formation. By this the first cycle of the curve is filled up, so that the 

 beginning of the cycle will about fall ui)on the boundary between Creta- 

 ceous and Eocene. In the Paris basin the Middle Eocene has twenty- five 

 alternations of strata and perhaps one or two breaks. Six oscillations 

 about correspond to twenty-five or thirty precessional periods. 



At the commencement of the cycles the mean value of the eccentric 

 ity is low; it rises in the middle of the cycle and sinks again towards 

 the conclusion. The position of the shore-lines must also depend upon 

 the mean value of the eccentricity. But as it increases very slowly 

 through very long periods, it will be very long before its action is to be 

 seen on the solid earth. The middle of the cycles ought thus to corre- 

 spond to the overflows of the sea, the beginning and close to the periods 

 of denudation which separate the formations. Breaks in the series of 

 beds may therefore be expected under high latitudes, especially at the 

 limits between the cycles. 



The boundary between Cretaceous and Eocene is indicated by what 

 Suess {Antlitz der Erde, ii, 7ter Abschn., p. 37G) calls a negative phase; 

 the sea had retreated in higher latitudes. During the Eocene it rose 

 again, and the Eocene sea had a great extension ; we iind its formations 

 even in the heart of Upper Asia. The limit between the Eocene and 



