254 FRAGMENTS OF SCIENCE 



number of cracks with this total width would relieve the 

 strain; that is to say, the sum of the widths of all the 

 cracks over the length of 100 miles would be 420 yards. 

 If, instead of comparing the width of the fissures with the 

 length of the lines of tension, we compared their areas 

 with the area of the unfissured land, we should of course 

 find the proportion much less. These considerations will 

 help the imagination to realize what a small ratio the area 

 of the open fissures must bear to the unfissured crust. 

 They enable us to say, for example, that to assume the 

 area of the fissures to be one-tenth of the area of the land 

 would be quite absurd, while that the area of the fissures 

 could be one-half or more than one-half that of the land 

 would be in a proportionate degree unthinkable. If we 

 suppose the elevation to be due to the shrinking or subsi- 

 dence of the land all round our assumed circle, we arrive 

 equally at the conclusion that the area of the open fissures 

 would be altogether insignificant as compared with that of 

 the unfissured crust. 



To those who have seen them from a commanding ele- 

 vation, it is needless to say that the Alps themselves bear 

 no sort of resemblance to the picture which this theory pre- 

 sents to us. Instead of deep cracks with approximately 

 vertical walls, we have ridges running into peaks, and 

 gradually sloping to form valleys. Instead of a fissured 

 crust, we have a state of things closely resembling the 

 surface of the ocean when agitated by a storm. The val- 

 leys, instead of being much narrower than the ridges, oc- 

 cupy the greater space. A plaster cast of the Alps turned 

 upside down, so as to invert the elevations and depres- 

 sions, would exhibit blunter and broader mountains, with 

 narrower valleys between them, than the present ones. 



