THE RECENT ADVANCE IN SEISMOLOGY 295 
view is that these sediments were deposited in a depth between that 
of the shallows and that of the deep sea (more definitely between 
depths of 80-100 and 900 meters)—a zone to which he has applied 
the name bathyal. Within this zone the geological rock formations 
are chiefly shales, clays, marls, schists, and compact and nodular 
limestones; and Haug finds a strong analogy between the distribution 
of fossils in rocks of this class which were formed during the Secondary 
era and the distribution of living forms within the bathyal zone of 
the ocean. 
Hall’s theory, which regarded the sediments of the geosynclinals 
as having originated in shallow water, required a most perfect equilib- 
rium to exist between the rate of depression and the rate of accumula- 
tion; provided the same lithologic character was to be maintained for 
great thicknesses; but this adjustment is less necessary if greater 
depths of the floor of deposition be assumed. Haug expresses the 
view that in the vast majority of cases a correspondence exists between 
the axes of folds subsequently developed in a geosynclinal and the 
axis of the geosynclinal itself, instancing many French examples. 
It is, however, the geographical distribution of the geosynclinals 
and their relation in position to former continents, in which the original 
contribution of Haug chiefly consists: 
The American authors, to whom is due the notion of geosynclinal, have 
always taken as the point of departure of their orogenic theories the fundamental 
idea that mountain chains form on the border of the oceans and that the continents 
increase by the addition of new chains successively more recent. According 
to this hypothesis, the geosynclinals should be born at the margin of the continents 
and the oceans, and should be exclusively of littoral sediments, and the zone of 
depression where the intensive sedimentation is going on should be separated 
from the high sea by a mere swell (bourrelet). It is easy to demonstrate that it 
is not under these conditions that the geosynclinals form; and that, far from 
originating at the margin of the oceans, they are always situated between two con- 
tinental masses and constitute the mobile zones between masses relatively stable.* 
As special cases in point the Himalayas and the mountain chains 
of central Europe are cited, and the general law is thus stated: 
(1) The geosynclinals, the essentially mobile regions of the earth’s crust, are 
always situated between two continental masses, the regions relatively stable ; 
(2) the geosynclinals constituted before their filling marine depressions of a very 
considerable depth.? 
t Loc. cit., p. 630. 2 Tbid., p. 632. 
