218 F. B. TAYLOR ORIGIN OF THE EARTH's PLAN 



of jt about 1,000 miles long lias been stretched to a length of nearly 

 3,000 miles ! 



It is probabl}^ much nearer the truth to suppose that the mid-Atlantic 

 ridge has remained unmoved, while the two continents on opposite sides 

 of it have crept away in nearly parallel and opposite directions. The 

 Cordillera of South America show that that continent moved a consider- 

 able distance toward the west and northwest in the Tertiary diastro- 

 phism; the movement of Africa appears to have occurred at a much 

 earlier date, apparently before the Mesozoic era. 



There are many bonds of union which sliow that Africa and South 

 America were formerly united. Their present forms and rehitions sug- 

 gest that the force which parted them was one that tended originally to 

 crowd the two parts toward each other — that is, it tended to make Africa 

 move south and South America north. But the release of strain was 

 found by a great diagonal fracture along which the crust divided in two 

 parts that crept away in opposite directions. Tlie mid-Atlantic ridge 

 remained unmoved and marks the original place of that great fracture. 



THE ANTARCTIC LAND 



This is the great southern horst, just as Greenland is the great north- 

 ern, but its role in the Tertiary movements appears on present knowledge 

 to have been less prominent. The pulling away from the Arctic regions 

 was prodigious, especially toward Asia; only Greenland remained un- 

 moved; whereas the whole of the Antarctic land appears to have held 

 fast, while only Australia and South America pulled away. No doubt 

 great rifts exist, corresponding to the pulling away of these two conti- 

 nents, but they appear to be submerged and obscured much more than 

 those of the north. Perhaps the Jeffreys deep, south of Australia, stands 

 in this relation to that continent, and possibly the Ross deep bears the 

 same relation to South America. 



THE .SOUTHERN HEMISPHERE THE COMPLEMENT OF THE NORTHERN IN 

 TERTIARY CRUSTAL MOVEMENTS 



Although the facts are fewer and perhaps not so clear in their import, 

 there seems still to be ample evidence that, excepting the southern part 

 of the Malay arc, those parts of the Tertiary mountain belt which fall 

 within the southern hemisphere were produced by crustal movements 

 which were directed in general from south to north or in the opposite 

 direction from those of the northern hemisphere. 



The abstract statement made above may now he extended so as to in- 

 clude the whole earth, thus : In the Tertiary mountain making the crustal 



