216 Maclure on Geology. 



and even suggested the first hint which afterward led to the 

 discovery of the marble. Doubts being entertained concern- 

 ing some of the geological relations of those rocks, a letter 

 was addressed to Mr. Maclure (then in Philadelphia) on the 

 subject. His answer is subjoined. 



In giving it to the public, the editor takes a liberty which 

 he hopes the respectable author will pardon, because his pro- 

 duction, although evidently never intended for the public eye, 

 contains statements and opinions of no small importance to the 

 young geologist, especially of this country. 



Geology, at the present day, means not a merely theoretical 

 and usually a visionary and baseless speculation, concerning 

 the origin of the globe ; but, on the contrary, the result of 

 actual examination into the nature, structure, and arrangement 

 of the materials of which it is composed. It is therefore obvious, 

 that the opinions of those men, who, with competent talent 

 and science, have, with a direct reference to this subject, ex- 

 plored many countries, and visited diflferent continents, are 

 entitled to pre-eminent respect. Saussure, by his scientific 

 journeys among the Alps, (although a limited district! has 

 given deserved celebrity to his own name, and, if it were pos- 

 sible, has thrown an additional charm of attraction over those 

 romantic and sublime regions. Dolomieu has made us familiar 

 with the productions and phenomena of volcanoes, those 

 awful and mysterious laboratories of subterranean fire. Hum- 

 boldt has surveyed the sublimest peaks of both continents, and 

 examined the structure of the globe amidst the valleys of 

 Mexico and the snows of Chimborazo and Pinchinca ; and 

 Werner, with opportunities much more limited, (confined in- 

 deed to his native country, Saxony) but with astonishing saga- 

 city and perseverance, deduced from what he saw, a classifica- 

 tion of the rocks of our globe, which, although not perfect, 

 has done immense service to the science of Geology. In this 

 distinguished group (to which other important names might be 

 added) Mr. Maclure has unquestionably a right to be placed. 

 Few men have seen so much of the structure of our globe, and 

 few have done so much with such small pretensions. His 

 work on American Geology is noticed with becoming respect 



