180 
MAJOR EARTH FEATURES 
means all regions of folding, and it is also wholly hypothetic to 
assume that geosynclines must be surrounded by continents. 
The relief of the earth’s crust is dominated by the contrast be¬ 
tween the continental platforms and the ocean basins. Continents 
and ocean basins are the two chief features of the earth’s surface. 
In comparison with them, all other features in the relief of our 
planet appear as architectonic by-products of secondary import¬ 
ance. 
The question of the relative permanency of the ocean basins and 
land masses is a fundamental one in our science, and since the 
middle of the last century has been the subject of repeated dis- 
N 
cussions by geographers, geologists, and geophysicists. It must 
not be in any way confused with the question whether the re¬ 
lation between land- and sea-surfaces has always remained the 
same or has changed repeatedly in the course of the earth’s his¬ 
tory. The problem should be stated as follows: Do the continen¬ 
tal masses and the ocean basins lie to-day practically in the 
same places which they occupied in the Cambric Period?, On 
practical grounds the question should be thus formulated and not 
extended to include an agreement of the present continental 
masses and ocean basins with those elevations and depressions 
which were formed at the first consolidation of the earth’s crust, 
since in paleogeographic research a reliable basis can be obtained 
only with the first appearance of fossiliferous sediments, whose 
exact age can be stratigraphically fixed. 
It would be of little value to discuss here in detail the historic 
development of the question of the relative permanence of the 
continental abyssal regions. On the one hand, many of the as¬ 
sumptions which served Dana and [especially] Lyell as starting 
points in the first conflict of their opinions; on the other hand, 
the excellent presentation of the status of the question given by 
Penck ^ in 1894, in his “Morphologic der Erdoberflache,” still 
holds good to-day in all respects. 
As a result of increasing knowledge and the constantly growing 
emphasis on the difference between the transgressing epicontinen¬ 
tal seas and the earth-encircling oceans with their mighty abyssal 
regions, the question of the permanence of continents and ocean 
basins has in general been gradually shoved aside in the sense 
2 Morphologic der Erdoberflache, I, p. 174, 1894. 
