334 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
ancient geologic epoch—at Paris as well as at London or at Vienna. 
T even believe, and here I coneglude this digression, that the greater 
part of our present seas cover the sites of ancient continents and 
may mark the place of future continents. 
This comparison between oceanic and continental geology presents 
a very extended program for our study. 
In the first place, continental geology includes the study of certain 
horizontal strata, such as the limestones, sandstones, schists, etc., 
a study called stratigraphy. Here especially are some formations 
deposited under the waters of ancient seas which formerly covered 
our globe. We shall very naturally find again at the bottom of the 
seas similar deposits in process of formation; the present composi- 
tion of these marine deposits will enlighten us as to the past of our 
geologic sediments. 
This present sedimentation in the seas is the part of oceanography 
which has most attracted the attention of geologists; it is likewise 
the best known phase of our subject and will interest us the longest. 
It proposes a multitude of questions: on the aspect of the deposits 
with relation to the topography of the bottom of the seas and on that 
so convenient hypothesis of horizontal stratification which, accord- 
ing to Sténon, is the basis of our geologic theories; then on the organic 
and chemical nature of these sediments; on the transformations that 
they have undergone by diagenesis at the very bottom of the sea. 
In this regard, especially, the problems that confront us are of pecu- 
liar interest. We know from geology that the strata emerged on 
the continents continue through all ages to undergo transformations 
which at times end in making them unrecognizable and one of the 
essential traits of which is the gradual elimination of the organic 
remains by their transition to a crystalline structure. This is what is 
called metamorphism or metasomatosis. In the present marine sedi- 
ments we shall come to see in actual operation phenomena which 
appear to me very closely to resemble those of metasomatosis and 
to which is given the name, also a bit barbarous, of diagenesis. 
These are modifications undergone by marine deposits at the bottom 
of the seas, consequently before their emergence: modifications 
which, for chemical reasons as yet not fully determined, seem to end 
in results very analogous to those of metasomatosis at the surface. 
And the geology of the sea bottom will also bring before us that 
other great branch of geologic formations called igneous rocks. We 
shall have a word to say about submarine volcanoes. 
Finally, no more than does terra firma remain immovable, does 
the sea escape results of internal movements. There are small, rela- 
tively feeble earthquake shocks. There are also the great geologic 
movements shown, by their two principal forms of vertical displace- 
ments and foldmgs. Finally, from some such movements of the 
