1 8 The Founders of Geology LECT. 



really disposed with much more regularity than had been 

 previously imagined. He surmised that, instead of being 

 dispersed at random, they are grouped in bands which have 

 a characteristic assemblage of minerals and a determinate 

 trend, so that when once the breadth and direction of one 

 of these bands is known, it will be possible, even where 

 the band passes into an unknown country, to tell before- 

 hand which minerals and rocks should be found along its 

 course. 



The first sentences of his remarkable Mtmoire et Carte 

 Mineralogique are well worth quoting. " If nothing," he 

 remarks, " can contribute more towards the formation 

 of a physical and general theory of the earth than the 

 multiplication of observations among the different kinds 

 of rocks and the fossils which they contain, assuredly 

 nothing can make us more sensible of the utility of such 

 a research than to bring together into one view those 

 various observations by the construction of mineralogical 

 maps. I have travelled with the view of gaining in- 

 struction on the first of these two points, and following 

 the recommendation of the Academy, which wished to 

 have my work expressed on a map, I have prepared 

 such a map, which contains a summary of all my 

 observations." 



The idea of depicting the distribution of the mineral 

 products of a country upon a map was not original with 

 Guettard or the Academy of Sciences. As far back as the 

 later years of the previous century a scheme of this kind 

 was submitted to the Eoyal Society of London, and 

 appears in the Philosophical Transactions with the quaint 

 title of " An ingenious proposal for a new sort of Maps of 





