the Displacement of Shore-lines. 427 



to onr hypothesis, the radii of the higher latitudes constantly 

 lengthen, while those of lower latitudes are shortened, yet 

 through long geological periods coast-lines return repeatedly, 

 during their displacements, to their old position. Thus A, de 

 Lapparent (Bull. Sac. Geol. France, ser. 3, vol. xv. p. 400) 

 says : — " I have indicated, in the Cotentin, an agreement 

 between the actual shores and those at which the sea stopped 

 at various epochs of geological history. I have there shown 

 shore-lines reproduced, almost without variations of altitude, in 

 the Hettangian, Sinemurian, Liassian, Cenomanian, Danian, 



Parisian, Tongrian, Pliocene, and present epochs , and 



that eight or nine times at least, since the Primary era, the 

 coincidence of the shores has been reproduced at the same 

 point ; " and in the same work (p. 277) he says : — " It is only 

 by tens of metres that, on the coast of the Cotentin, we must 

 reckon the differences between the successive levels of the seas, 

 from the Trias down to the present day." Here we see that 

 the variations of level have taken place with great regularity. 

 The sea has risen, and later on the land has been elevated ; 

 and these alternate risings and sinkings have occurred with 

 such regularity that the coast-line again and again, at long 

 intervals, has returned about to its old place. 



After this there seems really to be a possibility that our 

 hypothesis is sufl&cient to explain the displacements of the 

 shore-Knes w^hich have taken place. We have hitherto con- 

 sidered the conditions under hiah latitudes. Under lower 

 latitudes all may sink. Here " Horste ' may be formed such 

 as Suess supposes, and as to the occurrence of these localities 

 Lapparent's criticism is unsatisfactory. He has attacked 

 Suess's theory of " Horste " in its entirety, but he has cri- 

 ticised it specially only for such localities (Colorado, Vosges, 

 Black Forest, and the central plateau of France) as lie under 

 high latitudes. The localities named have (according to 

 Lapparent) risen more than their environment, which also is 

 quite in accordance with the opinion above developed. But 

 under lower latitudes, when a general sinking takes place in 

 the course of time, resistant parts will form true " Horste " in 

 Suess's sense. And it scarcely goes against our hypothesis 

 to assume, with Suess, that the Indian Ocean is formed, by 

 depression, and that Africa, Madagascar, India, &c. are 

 •' Horste," parts of the crust which have remained in position, 

 or which have sunk less than the neiohbourino- regions. In 

 these countries, so far as their geology is known at present, 

 there seem to be few marine formations of the Mesozoic and 

 Cainozoic epochs. 



I have said above that the different parts of the crust may 



