230 Reviews—Dr. Trautschold on the Level of the Sea. 
parallel disturbances, affecting the north of France from the Perche 
to the Artois, following a direction near to 130°. These disturbances 
are the result of a lateral compression which has produced, through- 
out this region, a succession of folds alternately convex and concave, 
or anticlinal and synclinal. Three of these folds, that of the Seine 
valley, that of the Bray, and that of Artois, have been particularly 
sharp, so that at many points faults have been produced. ‘This 
effect has attained its maximum in the Pays de Bray, where the 
Normandy lip or side of the disturbance has been elevated at certain 
points more than 500 métres above the Picardy side. Besides, 
throughout its course, this dislocation shows differences of intensity 
which appear to have an intimate connexion with the occurrence of 
former geological disturbances. 
“The dislocation of Bray, like that of Artois, appears to have 
occurred towards the close of the Eocene Epoch, between the period 
of the limestones of Saint-Ouen and that of the gypsum. Subsequently 
the region has been affected by fresh movements, contemporaneous 
with the diversion of the Beauce Lake, which is shown by two 
systems of conjugate directions: the first is the north-east and 
south-west system, of the valley of the Oise; the second, directed 
from west-north-west to east-south-east, is that of the hills of the Fon- 
tainbleau sands, as in the forest of that name in the environs of 
Paris. These two conjugate systems would be formed at the same 
time as the elevation of the Western Alps.” 
The memoir is illustrated by woodcuts, a neatly executed geolo- 
gical map, and three plates, showing the contours of the formations, 
and the principal hydrographic and orographic directions of the 
Pays de Bray. J. M. 
Il.—Sur wInvartapiziré pu Niveau pes Mers. By Dr. H. 
Trautschold. (Moscow, 1879.) 
ee author is not disposed to take anything for granted, but con- 
siders that doubting is the property of the learned. Thus, on 
reading an article wherein the fixity of the level of the seas since 
the beginning of geological time is assumed, he takes the oppor- 
tunity of disputing the assumption. 
His position is, that as certain parts of the earth’s crust rise from 
the bottom of the sea above its level, this latter must get lower. 
The surface of nearly all continents has formerly been sea-bottom. 
This surface emerged from the waters, partly in consequence of up- 
heavals, partly in consequence of the retreat of the ocean. Propor- 
tionate to the formation of continents, a part of the water of the 
seas was transported thither in the form of lakes, rivers, eternal 
snows, glaciers, and organic matter. Consequent on this process the 
water of the ocean is diminished and its level lowered. Proportion- 
ate to the cooling of the earth, ice accumulates near the poles, and 
upon the mountains, water is sucked more deeply into the crust, and 
the formation of hydrated minerals displays itself everywhere. 
The author points out that the prejudice as to the stability of the 
sea’s level has not always existed, and that in the middle of the last 
