454 EMERSON— RECURRENT TETRAHEDRAL DEFORMATIONS. 



north away from the great mass of Arabia-Africa. Later sinking 

 has occurred in part of the rearland and that these sinkings were 

 later is shown because they have often included parts of the chains 

 themselves as in the Crimea. These sinkings could not then be the 

 cause of the chains. Indeed, in the ^gean also they are known to 

 be much more recent than the chains. The land moved northward 

 in many divaricating folds, with enormous overthrusts far beyond 

 the competency of the sinking Mediterranean even in the most 

 favorable sections. The abnormally small size of the European 

 nucleus aided in this formation of the slope on which these wrinkles 

 could form and move northwardly in great overlaps which have 

 been the special study of Swiss and French geologists for many 

 years. 



While the depression of the Pacific by combining extensive 

 wedge action and eastward momentum from the sinking seems to be 

 a vera causa for the Andes and Cordillera, this is not possible for 

 the sinking of the Mediterranean where the force acting north- 

 wardly, the rotational effect of the earth is wanting, and so there is 

 no momentum, and being much smaller the wedge eft'ect would be 

 insufficient to make the enormous overthrusting of the Alps. More- 

 over the chains go west across Spain and east across Asia Minor, 

 extending in great loops northward far beyond the influence of the 

 sunken blocks of the Mediterranean and Black Sea. The great 

 virgation of the Alps and the sigmoid curves of Spain, the Car- 

 pathians and Balkans suggest a movement far north into narrowing 

 latitudes which crumpled the curves, while the Asian chains moving 

 in the opposite direction in an expanding area deploy flow-like, as 

 does a glacier moving out on a plain. These chains from Spain to 

 the Caucasus lie along the crest and northern slope of the old equa- 

 torial protuberance and when the equator was transferred south to 

 its present position this projection was unsupported and sunk, flow- 

 ing down northwardly in great convex loops. The slow southward 

 transfer of the equatorial protuberance dependent on the movement 

 of the pole prevented corresponding southward-moving chains, ex- 

 cept perhaps in the case of the Atlas range, or perhaps here the 

 sinking of the Mediterranean may have been effective. If the 

 transfer of the equator be found indefensible the mass of Africa 



