120 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



in Europe, were spared in the case of the other continents. 

 In them the knowledge so hardly won in Europe could at 

 once be adopted, and the help of experienced European 

 observers could be secured in carrying out pionner research 

 elsewhere. Thus geological data furnished within a few years 

 in foreign lands could often bear comparison with the results 

 that had demanded many decades or even centuries of work 

 in the European territories. Active co-operative research in 

 the other continents did not commence until after the period 

 with which this introductory chapter deals. 



North America was first brought into the field of geological 

 science. As early as 1752, Guettard had examined a collec- 

 tion of Canadian fossils, and had tried to apply to North 

 America the sedimentary horizons which he had erected for 

 Europe. He had gone so far as to construct a hypothetical 

 map showing the distribution of the various rock-formations 

 whose existence he had surmised. 



Of another character were the investigations of the Scots- 

 man, Maclure (1763-1840), who had been trained as a 

 mineralogist by -Werner. Maclure published in 1809 a treatise 

 and a map on the geology of the United States (Trans. A/ner, 

 Phil. Soc.). He distinguished the rock-formations according to 

 Werner's system, and showed that the primitive rocks pre- 

 dominate on the north and west of the Hudson, and form the 

 basement in the New England States; the transitional forma- 

 tions repose upon the primitive rocks and extend far west to 

 the Mississippi, where the Flotz or younger sedimentary forma- 

 tions begin. Maclure also gave a clear exposition of the 

 distribution of the Carboniferous formation in the Alleghanies, 

 in Pennsylvania, and in the West, of the absence of trap-rocks 

 in the Flotz formation, and the absence of porphyry, vesicular 

 rocks, and basalt in the whole eastern district of the United 

 States. He fully realised and depicted the simplicity and the 

 gigantic scale of geological structures in the United States. 



Maclure's comprehensive survey of the geology of North 

 America overshadows the many smaller works on local strati- 

 graphical details, such as those of Jefferson, Gibbs, Bruce, 

 JSilliman, and others. 



Long before geological research had begun in North America, 

 however, the presence of mammalian remains similar to those 

 of Siberia had been discovered. Dr. Mather, in 1712, reported 

 in a letter to Woodward the presence of bones of enormous 



