A SKETCH OF GEOLOGY. 



The name "Geology" is derived from the Greek words "ge," the earth, and 

 "logos," a discourse, thus indicating a science of the earth, a science investi- 

 gating the different materials of which the earth is composed, and also the 

 manner in which these materials are arranged. Geology gives us, also, the 

 history of our planet from its beginning to the present time examining all 

 the processes through which the earth has passed, from its original gaseous 

 condition until it acquired its present form and structure. It furthermore 

 enables us to obtain extensive and valuable information about the animal and 

 vegetable life which covered our globe during bygone ages. 



Geology is a science of comparatively recent date, though we find some geo- 

 logical knowledge among the ancient Romans and Greeks, and in the writings 

 of the middle age. All that knowledge, however, amounted only to a few 

 isolated speculations, nearly always based upon erroneous suppositions, and 

 never resulting in the establishment of a regular system. Geology as a science 

 was originated during the last century, but received its main development dur- 

 ing the present one. In spite of its short existence, it has outgrown many of 

 its sister sciences, and ranks to-day among the most important ones at the head 

 of the scale. Its founders and chief promoters are mainly found among the 

 English, German and French savants, and during the present century our own 

 country has contributed its full share to its advancement. The names of Lyell 

 and Murchison, of Leopold von Buch and Goldfuss, of Cuvier and Verneuil, 

 and of our own eminent geologist, Professor James Hall, of New York, and 

 many others, will be known to the students of this noble science through- 

 out the coming ages. 



Geology has for its territory the whole earth, as far as the same is accessible 

 to its investigations. These are not confined to the surface, but penetrate as 

 deep into the interior as artificial excavations for mines and artesian wells 

 allow. Still greater and better opportunities than these artificial openings, 

 which are limited in numbers and dimensions, are offered the geologist, for his 

 researches, by the peculiar figuration of our planet's surface, where deep 

 valleys alternate with high mountains, and where the strata are bent to such a 

 degree that we find them at one place deep below the surface, whilst at a dis- 

 tance of a few miles the very same layers may be outcropping at the slope of 

 a hill, or may even form the surface rocks of extensive districts. 



