252 FRAGMENTS OF SCIENCE 



of difficulty. Special localities might be found which would 

 seem to contradict every solution which refers the confor- 

 mation of the Alps to the operation of a single cause. 



Still the Alps present features of a character sufficiently 

 definite to bring the question of their origin within the 

 sphere of close reasoning. That they were in whole or in 

 part once beneath the sea will not be disputed; for they 

 are in great part composed of sedimentary rocks which re- 

 quired a sea to form them. Their present elevation above 

 the sea is due to one of those local changes in the shape 

 of the earth which have been of frequent occurrence 

 throughout geologic time, in some cases depressing the 

 land, and in others causing the sea-bottom to protrude be- 

 yond its surface. Considering the inelastic character of 

 its materials, the protuberance of the Alps could hardly 

 have been pushed out without dislocation and fracture; 

 and this conclusion gains in probability when we consider 

 the foldings, contortions, and even reversals in position of 

 the strata in many parts of the Alps. Such changes in the 

 position of beds, which were once horizontal, could not 

 have been effected without dislocation. Fissures would be 

 produced by these changes; and such fissures, the advo- 

 cates of the fracture theory contend, mark the positions 

 of the valleys of the Alps. 



Imagination is necessary to the man of science, and we 

 could not reason on our present subject without the power 

 of presenting mentally a picture of the earth's crust cracked 

 and fissured by the forces which produced its upheaval. 

 Imagination, however, must be strictly checked by reason 

 and by observation. That fractures occurred cannot, I 

 think, be doubted, but that the valleys of the Alps are 

 thus formed is a conclusion not at all involved in the ad- 



