TRANSLATIONS AND NOTICES 
OF 
GEOLOGICAL MEMOIRS. 
Lirnotoey of the Sras of the Orp Wortp. By M. Dertzssn*. 
A stupy of the deposits which are forming in the bed of existing 
seas presents great geological interest ; for it enables us to restore in 
imagination the seas of former epochs, and from the present to acquire 
a knowledge of the past history of our globe. 
The larger portions of the seas of the Old World have been 
explored by numerous soundings, which give their depth as well as 
the nature of their bed; consequently I have been able to extend 
in them the researches in lithology which I first commenced in the 
seas round the shores of France+. The method which I have fol- 
lowed is the same as that at first employed, and the results obtained 
are embodied in a map which has been recently laid before the 
Geological Society of London. 
Starting from the data furnished by the soundings of the hydro- 
graphic engineers, the submarine orography has been laid down by 
the aid of contour lines, and according to the method of Buache. 
Then I have endeavoured to separate as much as possible the 
rocks of the existing period from those of former periods. The first 
consist almost exclusively of unconsolidated (meubles) deposits; whilst 
the rocks already consolidated do not receive sedimentary deposits, 
and belong to the second series. The same tints have been given 
to all rocks which present the same lithological character, without 
reference to their age. It becomes, therefore, very easy to see how 
they are disposed over the vast surfaces which extend at the bottom 
of the seas, and to recognize the order of their distribution: it even 
becomes possible to recognize the geological relations which connect 
the existing deposits and submarine rocks with the strata which 
emerge in their neighbourhood. Let us recapitulate briefly the 
principal results obtained in some seas of the Old World. 
The Sea of Aral is of special interest, since it has been well 
studied by the Russian Navy, and because it offers at the present 
time the example of a great lake of salt-water. Its depth is slight ; 
for its bed is the continuation of the surface of the steppes which 
* Extract of a work in course of publication by Eugéne Lacroix, Paris. 
t “Mers de France et Mers Britanniques,”’ Comptes Rendus, April 1867 & 1868. 
VOL. XXVI.—PART II. c 
