OPINIONS OF VOLTAIRE AND LAPLACE REGARDING GEOLOGY. 313 
bottom ? Tbe mountains near Calais and Dover are of chalk ; 
therefore formerly they were not separated by water. This 
may be, but it has not been proved. The rock of Gibraltar and 
near Tangier, is of the same kind, therefore Africa and Europe 
touched each other, and there was no Mediterranean Sea. 
The Pyrenees, the Alps, and the Apennines, have appeared to 
many philosophers to be the debris of a world which has changed 
its shape several times. This opinion, long maintained by the 
Pythagorean school and by others, affirms that all the habitable 
globe was once sea, and that the sea was long land/ 
‘This opinion has been more than once credited, by the 
examination of those beds of shells which are found heaped up 
in layers in Calabria, in Touraine, and other places, in earth 
situated far from the sea. Peally there is a great appearance 
of their having been deposited during a long succession of ages. 
The sea, which has retired some leagues from its ancient shores, 
has returned, little by little, in other spots. From this almost 
insensible loss the right to believe in the ocean having covered 
the globe for a long time, is concluded. Frejus, Narbonne, and 
Ferrara, are no longer seaports : half of the little country of 
East Frisia has been submerged by the ocean ; therefore, for- 
merly, whales swam for ages over Mount Taurus and over the 
Alps, and the bottom of the sea was once peopled with men. 
This system of physical revolutions of the world has been 
strengthened in the minds of some philosophers by the discovery 
of M. de Louville. It is known that this astronomer went 
expressly to Marseilles, in 1714, to observe if the obliquity of 
the ecliptic was still the same as it had been determined by 
Pytheas nearly 2000 years before : he found it less by 20'. 
That is to say, according to his views, the ecliptic had approached 
the equator \°, which proves that in 6000 years the approach 
would be an entire degree. This supposed, it is evident that 
the earth, besides its known movements, has another which 
makes it turn on itself from one pole to the other. It would 
happen that in 23,000 years the sun would be over the equator 
for a long period, and that in a period of about two million of 
years, all the climates of the world would have occurred con- 
secutively, in the torrid zone and in the glacial zones/ 
‘ Why, they say, be frightened about a period of two mil- 
lion of years ? There are probably longer ones between the 
reciprocal position of the stars. We know already of a move- 
ment of the globe which is accomplished in more than 25,000 
years, and it is that of the precession of the equinoxes. The 
passing away of thousands of millions of years is infinitely 
less in the eyes of the Eternal Architect of the universe, than 
are the turnings of a wheel in the twinkling of our eyes. This 
new period imagined by the Chevalier de Louville, and main- 
