142 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



Text-books and Handbooks of Geognosy and Geology. The 

 Text-books of Geology which appeared during the period 

 between 1790 and 1820 showed an improvement on the 

 speculative works of the preceding periods by their more 

 matter-of-fact treatment of the subject. They may be taken 

 as a standard of contemporary knowledge on geological 

 subjects, and deserve special mention. 



Most of the German text-books during this period were 

 simply repetitions of Werner's teaching. As a rule mineralogy 

 and geognosy were combined in the larger text-books, but in a 

 few cases geognosy was published separately. Voigt's Practical 

 Knowledge of Mountains (Weimar, 1792) was one of the best i 

 known, and it differed from Werner's teaching on several 

 important points, such as the origin of basalt and the causes 

 of volcanism. On this work Dietrich L. G. Karsten in great 

 measure based his Mineralogical Tables (1800), which had a 

 wide circulation. 



The most complete and trustworthy text-book founded 

 on Werner's teaching was that by Franz Ambros Reuss 

 (Leipzig, 1801-6), in which six volumes are devoted to 

 mineralogy and two to geognosy. The first volume of the 

 geognosy or geology begins with a short introduction on the 

 compass and domain of geognosy and the method of geognostic 

 study. The first chapter treats the earth as a whole in its 

 relation to other bodies of the universe, and states the most 

 important facts of astronomy and mathematical geography. 

 A second chapter is devoted to physiographical matters, the 

 present constitution of the earth's surface and atmosphere, and 

 the changes wrought on the earth's surface by existing natural 

 agencies. The third chapter is occupied with the solid crust, 

 describes the various kinds according to their composition and 

 structure, their age and origin, and gives an account of the 

 hypotheses concerning the origin and development of the 

 earth. The rocks are sub-divided in five "formation suites," 

 according to Werner. The fourth chapter contains a very full 

 description of the regional masses of rock extending through 

 mountain-systems or over wide areas. These are enumerated 

 in the order of the "formation suites," and a careful account 

 is given of their composition and texture, stratification or 

 jointing, geological age, origin and occurrence, and the fossils 

 or ores contained in them. A special chapter on metalliferous 

 ores concludes this work, the contents of which show that the 



