222 THE BEATTTIES OB" NATURE chap. 



miles, the Ardennes from 50 to 25 miles, 

 and the Appalachians from 153 miles to 

 65 ! Prof. Gumbel has recently expressed 

 the opinion that the main force to which 

 the elevation of the Alps was due acted 

 along the main axis of elevation. Exactly 

 the opposite inference would seem really to 

 follow from the facts. If the centre of force 

 were along the axis of elevation, the result 

 would, as Suess and Heim have pointed out, 

 be to extend, not to compress, the strata; 

 and the folds would remain quite unaccounted 

 for. The suggestion of compression is on the 

 contrary consistent with the main features of 

 Swiss geography. The principal axis follows 

 a curved line from the Maritime Alps towards 

 the north-east by Mont Blanc and Moiite 

 Rosa and St. Gotthard to the mountains over- 

 looking the Engadine. The geological strata 

 follow the same direction. North of a line 

 running through Chamlaery, Yverdun, Neu- 

 ch&tel, Solothurn, and Olten to Waldshut on 

 the Rhine are Jurassic strata ; between that 

 line and a second nearly parallel and running 

 through Annecy, Vevey, Lucerne, Wesen, 



