Reviews— Professor Suess’ The Face of the Earth. 179 
With respect to deep-sea accumulations it is remarked: ‘‘ We may 
conceive that little calcareous shells sink to the bottom in great 
quantity. They are dissolved at great depths, but accumulate in 
moderate or lesser depths. In the abysses red clay is deposited only 
in trifling quantity, but on those submarine elevations which rise 
above the level at which carbonates are dissolved, accumulation occurs. 
The result is an exaggeration of the relief. Thus the depths persist, 
while the ridges increase in height, and may even grow into peaks.” 
Moreover: ‘‘ During a long period of rest not only may a great sockle 
of limestone arise, but at some remote period, when the level of the 
ocean was higher, the deposit of limestone may even have grown up 
to a height above the sea-level as it now exists. It has then been 
denuded in terraces owing to intermittent negative movement.”’ 
Concerning the views of Darwin and Dana on atolls the author 
observes: ‘‘ It must still be admitted that the depth of the enclosed 
lagoon has not yet been completely explained. Thus, the view that 
the crown has been built up by corals during positive movement has 
still some foundation.” 
With regard to the great African fractures it is remarked: ‘‘ We 
must not form too rigid a conception of such troughs, as though they 
were strips of land let down between two parallel faults. Step 
faults are to be seen on Lake Tanganyika and in the lava fields which 
lie before Mount Kenya, on the west coast of the Red Sea also, and 
more to the north on Mount Lebanon and the slopes of the Jebel 
Ansarieh. We shall form a more correct picture if we think of 
these step faults as repeated on both sides, down to the middle of the 
valley bottom—many long strips, which become wedge-shaped below, 
being let down along them to unequal depths. In this way horsts 
have been left standing within the field of subsidence.”’ 
Considering the vast extent of the area involved it is regarded as 
impossible to explain the situation from local causes, and the author 
is led to assume the existence of tensions in the outer crust of the 
earth: the phenomena being due to a rending asunder caused by 
contraction, the fissures having opened from above downwards. The 
author’s general conclusions with regard to dislocations of great 
magnitude are that they have resulted from movements caused by 
diminution in the volume of the planet. 
Great part of the present work is taken up with an account of the 
influence of the Asiatic system of disturbances on the European and 
other areas, and the structure of the Alpine regions is described in 
considerable detail. The repetition of foldings along the same lines is 
discussed, and in the course of the work the relations between the 
great geological systems in different areas are dealt with. Brittany, 
the London Basin, the Mendips, South Wales, and Malvern all come 
under notice; likewise the mountain regions of North America and 
Northern Africa, the main features of Australasia and Polynesia, the 
festoons of islands, and the mountain system of the Andes. 
In order fully to grasp the complicated structures and the sequence 
of events discussed by the author, each volume must be read steadily 
through with the aid of maps; and we are glad to learn that the 
fifth and concluding volume will comprise the plates to which reference 
