Geological Results of the Earth’s Contraction. 179 
agency of contraction alone, without the causes of “ souléve- 
ment’ usually appealed to, will account for the various changes 
of level which the continental areas have undergone. He rejects 
the idea of an elevating force which can raise mountains or con- 
tinents, except such as is incidental to contraction. The princi- 
pal points in Prevost’s theory have already been presented in the 
preceding volume of this Journal, on page 355; and below we 
have given in a note a part of his explanations. 
The reader will perceive that although the main principles of 
Prevost are sustained by the writer in this and his former paper, 
the manner in which these principles are carried out, is in some 
respects a little different, especially in the idea that the oceanic 
areas have been the more igneous parts of the globe, and for this 
reason have contracted. most ;+ that certain orographic changes 
over the continents are due to contraction beneath the oceanic 
regions, and that the fissurings and mountain elevations have for 
is reason taken place in some instances near the margin of a 
continent, or near the limit between the great contracting and 
the non-contracting (comparatively non-contracting) areas. ‘The 
elliciency of the cause of contraction has appeared to the writer 
to be wider and more evident, as the subject has received closer 
oy rece Ge the study of it has naturally led to modifications 
orm 
The outeg if true does away with the most incredible of geo- 
ical dogmas,—the idea of a force acting beneath the continents 
which can raise them bodily with their load of mountains. ‘The 
mind unprejudiced naturally asks, where does this force reside? 
how does it act? What fills the void left by the raised 
continent? Why, after an earthquake has passed, should not a 
mass of rock as large as the Andes and half of South America, 
Sink back again to its place? 
before the change of level. If, on the other side, we view as submerged all the 
winks of existing continents and the islands - which marine deposits occur in 
orizontal position 3 if we place beasash the water the great part of the points of 
surface now existing as mountains, w aver is supposed to have risen since 
the formation of these marine deposits, we cannot but see that there would be no 
sae for vegetation or terrestrial animal life, none for the gre at lakes w 
Water animals and plants, and none for the ingen te t aie of 
nic productions are met with in ancient 
“Are we gue then forced to admit that while the bottom of + sea has ae 
raised above the level of the sea and made dry land, by a series of displaceme 
i i nee; and in mess a 
Way that the depressions formed were Ceaat extee the eleva a ition 
contrary eff 
AB rds = ae re ench has a Fores which oo ib pt belong to our 
upheava 
or eh transl tars avd hes impli a following ‘ou B rabo : e must therefore 
ascribe the cause [of changes of level] to the eat peither to i hat ground which 
is under the sea, or ‘ei at which becomes flooded by it, but rather to that which 
lies beneatly the sea, isi ovab ‘ble and on account of its humidity, ean be 
altered with greater celerity.” _ (Principles of Geology, vol.i; Strabo, Geog., lib. 1.) 
