86 
POPULAR SCIENCE REVIEW. 
GEOLOGY AND PALAEONTOLOGY. 
Formation of Mountains. — M. de Lapparent has an excellent article on 
this subject in the Revue des Questions Scientifiques for July last. He points 
out that the changes of position, the elevation, and especially the folding, of 
strata observed in mountainous districts are due to energetic lateral com- 
pression. Elie de Beaumont taught that mountain-chains do not occupy the 
centres of continents and show symmetrical slopes on both sides, hut that they 
are to he found near the sea, and have a precipitous slope on the side facing 
the sea, whilst the opposite side slopes gently away, forming the mass of 
the continent, and usually terminates in the opposite ocean hy a line of low 
country. This view has been formulated as a law hy several geologists, espe- 
cially in America, where the long line of the Rocky Mountains and the Andes 
furnish such a striking example in its support; and Professor Dana has 
added the following rider to it, that when two chains of elevations form the 
two shores of a continent, the one facing the largest ocean is the higher one. 
M. de Lapparent indicates that in order to apply these principles to the Old 
World mountains, and especially to those of Europe, it is necessary to force 
the facts a little, and hence he is led to the belief that while it is perfectly 
true that chains of mountains are always formed in the vicinity of the ocean, 
it is necessary, in order to understand their distribution, to consider the 
geographical conditions that prevailed at the period of their formation. He 
sums up his views in the following formula : — ■ At the epoch when a chain of 
elevations has just attained its principal relief, it consists of two slopes of 
very unequal inclination, one of which, gently inclined, is connected with the 
continent, while the other, which is abrupt, directly faces the sea/ Thus the 
Pyrenees, which are shown by geological evidence to have been elevated 
after the formation of the Nummulitic and before that of the Miocene 
deposits, were united by a gradual slope towards the south with the Spanish 
continent, while the foot of the precipitous northern face was washed by the 
Miocene sea. The Alps date from the interval between Miocene and Pliocene 
times. To the north they joined on by a gentle slope to the plains of northern 
Germany, while towards Lombardy they formed a vertical wall, at the foot 
of which were deposited the sediments of the Sub-apennine sea. M. de 
Lapparent refers to other European chains, and then formulates the following 
general law: — ‘A chain of mountains, at the moment of its formation, 
always occupies a littoral situation ; it does not depart from this afterwards, 
except when the continent is enlarged by new additions obeying the same 
law. If, therefore, at the present day, the Scandinavian mountains on the 
one hand and the Cordillera of the Andes on the other, emerge directly from 
the depths of the ocean, this is because these two chains belong to the most 
recent formations which have been produced on the globe ; and geology, as is 
well known, fully justifies this conclusion/ 
From the consideration of the soundings which have been so rapidly 
accumulated of late years, M. de Lapparent arrives at the conclusion that the 
great depths of the sea, as a general rule, are the counterparts of the great 
elevations of the land, and lie directly at their base, and hence he concludes 
that 1 at the moment when the profile of one of the lines of relief of the 
