88 B. K. BMBBSON — TETRAHEDRAL EARTH : INTERCONTINENTAL SEAS 



the Caspian, or where the northern Adriatic and .Egean liave sunk in 

 whole or part almost within the recent period. 



It may be asked why this zone of sinking and compression appeared 

 only on the northern slope of the former equatorial ring, and the answer 

 would be that as the equator moved southward across Africa the dimin- 

 ished protuberance was carried to its present position, producing here 

 an opposite tendency to elevation and rest. 



The maps show (see plate 14, page 78) the areas between the former 

 and the present equator to represent the longest east-west reaches of the 

 passive tablelands characterized by the absence of folding and by the 

 vertical sinking of great blocks, like the Dead sea, the Red sea, the Aden 

 gulf, and Tanganyika, in all this agreeing well with its assumed relations. 



Particular description of the zone with discussion of the exceptional char- 

 acter of the Asiatic chains. — Around the Mediterranean we know the 

 great mountain chains east to the Caucasus are moved mainly north- 

 wardly because they bend in great loops convex to the north between 

 the resisting forelands of Auvergne, Bohemia, and the Sudetic ranges. 

 This is the conclusion of Suess. If they had been caused by a thrust 

 from the south, the most compressed and overturned chains would be, 

 as in the Appalachians, nearest the causative force, or on the south. 

 If they had been caused by moving as a plastic mass down a slope, the 

 most compressed chains would be at the north. The latter case is the 

 true one, as the most comprimated and overthrust chains are the north- 

 ern Alps, as in the Todi-Windgallen group or north of Mont Blanc. 

 This is the suggestion of Reyer. It is as if the old land of Africa 

 has most resisted collapse, making a low slope down which the mass 

 moved, forming the strongest chains at the front of the sliding where 

 the forward motion has been greatest. There was locally partial thrust 

 to the south, as the sinking blocks acted like the toggle-joint of a primi- 

 tive printing press, and gave southward motion to the* Atlas. 



Such a local sliding to the northwest seems well established for a great 

 area of the western Alps, where between Geneva and lake Thun and 

 probably much farther in both directions and with the full width of the 

 line between Martigny and Vevay the Mesozoic rocks have slid out 20 

 kilometers over the Tertiary foreland and rest now rootless on Flysch 

 and the red Molasse. They have torn off and transported great masses 

 of the crystallines off which they have come.* 



In Asia, on the other hand, from the Caspian to Molucca, as there was, 



* M. Lugeon : Lea grandes dislocations des«Alpes de Savoie. Archives <les Science phys el mat. 

 4 Period 2, l-i, 1896. Review. Neues Jahr. L899, 2d vol , p. 404. II. Schardt : Die exotisehen Gebieto, 

 Klippen, und Bldcke am Nordrande der Schweitzer Aipen. Eclogse. Geol. Helv. V. 233, 1898. Re- 

 view. Neues Jahrbuch, vol. 1, 1900, p. 87. 



