434 LIFE OF HORACE BENEDICT DE SAUSSURE 



to the story of the evolution of our planet. In this connection he 

 insisted on the value of the examination and comparison of fossils, 

 about which the old naturalists had frequently made absurd 

 blunders. He recognised in the Alps the typical structure 

 that is repeated in so many great ranges, a core of granite and 

 crystalline schists forming the central axis, flanked on either side 

 by limestones showing a writing-desk formation that is, dipping 

 steeply on the flanks of the central crystalline core while their 

 slope declines gradually towards the outer foot-hills, which are 

 composed of more recent beds of softer material. He showed 

 that the base of the secondary rocks in the Alps is formed of a 

 conglomerate, marking a pause between the formation of the 

 primary and secondary mountain chains, and that this pheno- 

 menon is again met with at the base of the tertiary range . Though 

 at first reluctant to recognise any upthrust capable of raising the 

 mountains and dislocating their materials, he was gradually led 

 to admit that the stratified rocks had been originally deposited 

 in a horizontal position, and as a consequence that the dip of the 

 strata must be accounted for by the action of forces subsequent 

 to the formation of the earth's solid crust. Wherever he found 

 that joints, perpendicular to the stratification, were inclined at a 

 sharp angle to the horizon, he accepted the fact as conclusive 

 evidence that the mass of the mountain had shifted from its 

 original position. 



Conscious as he was of the great influence of atmospheric con- 

 ditions in moulding the earth's surface, de Saussure did not limit 

 his investigations to its solid crust. He was equally interested 

 in the conditions of its outer envelope. 



To the advance of the kindred science of meteorology he made 

 very important contributions. It is true that he took up and 

 pursued its study rather for its bearing on other branches of 

 inquiry than for its own sake, and that his attention was mainly 

 concentrated on the comparison of meteorological phenomena at 

 different altitudes and the practical application of them in the 

 measurement of heights . But his patience and accuracy in observa- 

 tion, coupled with his very exceptional ingenuity and adroitness 

 in inventing and constructing instruments, made him the leading 

 meteorologist of the Alps, and set an example to be followed 

 by many observers to whom a wider field of observation has 



