Ill 



Lehmann 97 



the title VersucJi einer Geschichte von Flotz-Geburgen, etc. 

 It gives the results of the author's own observations 

 among the rocks of the Harz and the Erzgebirge. He 

 recognized three orders of mountains. 1st, Those which 

 appeared coeval with the making of the world ; 2nd, those 

 which arose from a general alteration of the ground ; and 

 3rd, those which have been formed from time to time by 

 local accidents. The first order is distinguished not only 

 by the greater height of its members, but by their internal 

 structure. The rocks are less various, their strata are not 

 horizontal but vertical or inclined, and their layers are 

 neither so weak nor so multifarious as those of the other 

 groups. Nor are they mere superficial deposits, but they 

 plunge down into unknown depths into the earth's interior. 

 The second order, or Flotz-gebirge, are of much younger 

 date, and have arisen from the successive deposit of sedi- 

 ments from water that once covered their sites, these 

 sediments being now seen in flat sheets or strata piled 

 above each other to no great height. Lehmann showed 

 that these sedimentary deposits contain abundant petri- 

 factions, such as remains of wild animals, shells, plants 

 and trees. He gave a number of sections to show the 

 order in which the strata succeed each other, remarking 

 that the coarser sediments were generally lowest, while 

 limestone came at the top. His profiles of the succession 

 of strata showed a remarkable grasp of some of the 

 essential features of tectonic geology. It is singular that 

 these suggestive examples should not have had more 

 imitators during the latter half of last century. Nothing 

 could be more precise and distinct than Lehmann's demon- 

 stration of the stratified nature and aqueous origin of the 



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