MOVEMENTS AND DEFORMATIONS OF THE EARTH'S BODY. 547 



Each member of the minor group is an irregular chain of depressed 

 pits rather than a single continuous deep, unless the Arctic depression, 

 of which little is now knoAvn, proves an exception. They lie between 

 the greater segments at what may be conceived to be points of critical 

 working relations, and are accompanied by small elevated blocks. The 

 Caribbean, the Mediterranean, and the Bornean regions are the seats 

 of the greatest present volcanic and related activities. 



In a general view, there are then four great sunken quadrilaterals 

 and four great elevated triangles, with minor attendants in each class. 

 Lest fondness for simy)licity and symmetry lead too far, we must hasten 

 to observe that the dimensions are not alike in either class. The Pacific 

 segment is more than twice the size of any other basin segment, and 

 four times that of the North Atlantic. The Eurasian triangle is more 

 than twice the average size of the other land segments, and nearly three 

 times that of the South American. Nor is there any large common 

 divisor of api)roximate accuracy. This is not at all strange if the earth 

 be regarded as a body of somewhat heterogeneous composition which 

 naturally shrank in rather irregular segments. On the other hand, 

 this irregularity is somewhat strange if the earth has evolved from a 

 very homogeneous and symmetrical, primitive, fluid state. It is also 

 a serious consideration in any theory that appeals to crystalline form, 

 or analogy, as in the doctrine of a tetrahedral earth. 



Roughly approximated in millions of square miles, the major de- 

 pressed segments are as follows: the Pacific, 60, the Indian, 27, the South 

 Atlantic, 24, and the North Atlantic, 14, leaving 8 for minor depressions. 

 The elevated segments are Eurasian, 24, African, 12, North American, 

 10, and South American, 9, leaving 10 for the minor blocks. 



If these segments be regarded as the great integers of body-move- 

 ment, two-thirds of them taking precedence in sinking and the other 

 third in suffering distortion, it is easy to pass to the conception of sub- 

 segments, moving somewhat differently from the main segments, so as 

 to aid in their adjustment to one another, and thus to the conception of 

 plateaus and deeps. It is easy also to pass to the conception of mutual 

 crowding and crumpling at the edges of these segments, accompanied 

 by fracture and slipping. These conceptions perhaps represent the 

 true relations between the massive movements of the abysmal and 

 continental segments, as well as the less massive plateau-forming 

 movements and the mountain-forming distortions. The mountains 



