44 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



rocks of the next periods; his clear conception that the oldest 

 inhabitants of the ocean had become extinct and been 

 succeeded by younger forms; his allocation of the early home 

 of the large Mammalia in Polar districts; and his belief, based 

 upon the distribution of land faunas, that the Old and New 

 Worlds had once been united as a wide Northern Continent. 



The weaker features of Buffon's work are his views about the 

 origin of mountains and valleys, which are far behind those 

 of Steno, and appear to have been taken for the most part 

 from the Telliamed. He also neglected to incorporate the 

 important results attained by Lehmann, Fiichsel, Arduino, and 

 other stratigraphers. At the same time, Buffon was undeniably 

 one of the most gifted exponents of that speculative direction 

 which characterised the geological writings of the sixteenth, 

 seventeenth, and eighteenth centuries. This period, however, 

 contributed a large amount of useful material towards our 

 knowledge of the earth, and its many theoretical failures 

 brought men at last to a clearer preception that the materials 

 for an accurate history of the earth must be looked for in the 

 earth itself. But the key had not yet been discovered to the 

 solution of a chronological succession of rock-formations ; the 

 study of stratigraphy was still in its infancy, and the merest 

 beginning had been made in the investigation of deformation 

 of the crust and mountain structure. 



Volcanoes and Earthquakes. The phenomena of volcanoes 

 and earthquakes have always attracted a large share of 

 attention from geologists, not only in virtue of their majesty 

 and splendour, but also because of their destructive effects 

 upon human life and property. The philosophers of antiquity 

 for the most part associated volcanoes and earthquakes with a 

 molten earth-nucleus, or with special subterranean centres of 

 eruptivity, and the majority of the authors in the sixteenth, 

 seventeenth, and eighteenth centuries supported one or other 

 of these views. 



Martin Lister had a theory that when sand or other material 

 with an admixture of sulphur weathered in the atmosphere, the 

 sulphur became heated and exploded, causing volcanic erup- 

 tions. Lemery, in 1700, put Lister's theory to experimental 

 test; he showed how a mixture of sulphur, iron filings, and 

 water imbedded in earth becomes heated, and finally bursts 

 ope'n the earthy covering and emits flame and vapour. 



