428 Probable Caiise of the Displacement of Shore-lines. 



be assumed to haA^e clifFerent powers of resistance against the 

 interior pressure. This may, in fact, be concluded from the 

 fact that the surface is uneven, and that old, originally hori- 

 zontal formations have been upheaved unequally at different 

 spots. In other words, there is an inequality of the surface, 

 which has a deeper cause than the operation of eroding 

 forces. 



Changes of the earth's crust in reality happen in the most 

 various degrees at different times. The greatest convulsions 

 occur in the folded mountain-chains, and this has been the 

 ease in all geological periods. It is worthy of note that 

 places where great foldings took place in ancient times seem 

 to have been subsequently unaffected by processes of folding"^. 

 For upon the abraded summits of old folds there often lie 

 other old formations in an undisturbed horizontal position. 

 The most highly folded chains are also those in which plica- 

 tions have been continued to the latest timef. Along both 

 sides of the Pacific Ocean from Cape Horn to the Aleutian 

 Islands, and o])posite to this along the east coast of Asia as 

 far as the Sunda Islands, strike mighty chains associated with 

 series of volcanoes ; and from the Himalaya through the 

 Caucasus, Balkans, Pyrenees, and Atlas a similar series of 

 vast chains stretches through localities which are often 



• • • 



volcanic. These highest mountains of the earth are also the 

 youngest ; they are still the least affected by the tooth of time. 



But these strongly folded localities are of small extent in 

 comparison with the other parts of the earth^s surface. 



On both sides of these folds there are, namely, great 

 plateaux and plains, quite or nearly without any plications, 

 and, on the whole, with undisturbed horizontal beds. These 

 are Suess's "tables" (Tafeln). Africa, Western North 

 America (in the Eastern there are no younger jdications than 

 from Carboniferous times), Brazil, Australia, Arabia, Persia, 

 India, Siberia, and Russia are such " tables,'^ in which the 

 crust is much less disturbed. And no doubt the same thing 

 applies to the sea-basins, or at any rate to the greater part of 

 of them. 



When the sidereal day lengthens the sea at once adjusts 

 itself to the new conditions. It sinks under the lower and 

 i-ises under the hioher latitudes. Accordino- as the interior 



* If the earth's axis, as some astronomers {e.y. Gyldeu) tliink, may 

 shift its position in the course of time, calculations as to tlie pressure 

 produced by the lengtheuiug' of the day will also change, and the situations 

 of the parts of the crust exposed to the greatest pressure will also shift. 



t The following summary is founded upon Suess's interesting studies 

 in his g-reat w^ork Antlitz der Erde. 



