lOO LAMARCK, HIS LIFE AND WORK 



continents, they were upheaved by violent convul- 

 sions. He therefore required alternate periods of 

 general disturbance and repose." 



To Hutton, therefore, we are indebted for the idea 

 of the immensity of the duration of time. He was 

 the forerunner of Lyell and of the uniformitarian 

 school of geologists. 



Hutton observed that fossils characterized certain 

 strata, but the value of fossils as time-marks and the 

 principle of the superposition of stratified fossiliferous 

 rocks were still more clearly established by William 

 Smith, an English surveyor, in 1790. Meanwhile the 

 Abb6 Hauy,the founder of crystallography, was in 1802 

 Professor of Mineralogy in the Jardin des Plantes. 



Lamarck's Contributions to Physical Geology; his 

 Theory of the Earth. 



Such were the amount and kind of knowledge re- 

 garding the origin and structure of our earth which 

 existed at the close of the eighteenth century, while 

 Lamarck was meditating his Hydrogeologie, and had 

 begun to study the invertebrate fossils of the Paris 

 tertiary basin. 



His object, he says in his work, is to present cer- 

 tain considerations which he believed to be new and 

 of the first order, which had escaped the notice of 

 physicists, and which seemed to him should serve as 

 the foundations for a good theory of the earth. His 

 theses are : 



I. What are the natural consequences of the in- 

 fluence and the movements of the waters on the sur- 

 face of the globe ? 



