186 prof. w. j. sollas on [May 1903, 



site ; between the first and third a similar great segment has disap- 

 peared into the Indian Ocean, but larger fragments project above the 

 sea-level, such as Madagascar, and more numerous volcanic islands, 

 such as Mauritius and the Seychelles. Finally, the segment between 

 the second and third is only jjartly submerged beneath the sea, its 

 site being occupied by folded mountain-chains and great inland 

 seas, like the Mediterranean and Black Sea. A falling in of an 

 imaginary dome has been spoken of, but this is not a necessary 

 deduction ; a trilobed form may have been original, and the 

 fracturing of which we possess independent evidence may have 

 affected portions of these lobes. 



Outside the margin of the imaginary dome is an encircling sea 

 for nearly two-thirds of its circumference, but over against the 

 northern one-third symmetry is at present disturbed by continental 

 land, which, however, was not in existence, at all events to the same 

 extent, in the early stages of terrestrial development. 



The boundary of the circum-African seas is afforded by the great 

 Pacific belt of continents. Commencing with the Antarctic mass, 

 which lies symmetrically about our mean directive circle, we pass 

 to South America, which projects a little more towards the African 

 pole ; then to North America, which sways completely to the 

 Pacific side of the directive ; next to Asia, which swings over to 

 the African side ; and lastly to Australia, which crosses over to the 

 Pacific side. Thus the continental belt is an undulating one, but 

 its most recent mountain-foldings lie almost wholly on the Pacific 

 side of the directive, and nearfy tangential with it, the great excep- 

 tion being that of the Eurasian festoon of arcs which lies on the 

 African side. The belt is also interrupted, and that more or less 

 symmetrically, as will be seen from figs. 1 & 2, pp. 182-83. 



Beyond the continental belt lies the Pacific Ocean, covering 

 nearly an entire hemisphere, with an approximately symmetrical 

 distribution about the western morphological pole. A section taken 

 through the globe along a great circle, of which the morphological 

 axis and the East Indies-South American axis are two of the 

 diameters, would have roughly a pear-shaped form. 



In attempting to discover an explanation of this figure, our 

 thoughts naturally revert to Prof. G. H. Darwin's theory of the 

 evolution of the earth-moon system, and Prof. Darwin has himself 

 attempted to correlate the continental distribution with tidal effects. 

 The Kev. 0. Fisher also has suggested that the Pacific Ocean might 

 represent the ' scar ' left on the separation of our satellite. It is 

 probable that the tidal deformation which gave origin to the moon 

 was not the last of its kind ; it may well have been followed by 

 others, which, without producing a second satellite, may yet have 

 given to the earth a figure approaching the dumb-bell-like form, 

 and of this a reminiscence may be retained in its present shape. 



The moon must itself have produced a tidal effect, and could 

 scarcely have been without influence of another kind on the 

 primaeval atmosphere, which for some time after the origin of the 



