On the Determination of the Position of Strata in Stratified Rocks. 

 By L. A. NECKER, Honorary Professor of Mineralogy and 

 Geology in the Academy of Geneva, &c. 



(Read 6th February 1832.) 



IT has always appeared to me, that the study of the stratification 

 of rocks and of mountain masses, ought to be one of the princi- 

 pal objects of a geological observer. Many of the most import- 

 ant facts in geology have been ascertained by the consideration 

 of the position of strata. Among these facts, the relation exist- 

 ing between the direction and the inclination of the strata and 

 the unstratified rocks, to whose presence the change in the posi- 

 tion of the beds from an horizontal to an inclined, and some- 

 times even to a vertical situation, is now generally attributed, is 

 one of the most conspicuous. It is only by an accurate determi- 

 nation of the position of the strata in any mountain-chain that 

 the real direction of the line of elevation of that chain or its mi- 

 neralogical axis may be determined. 



However, such a determination is not always so easily accom- 

 plished as it is in mines, in quarries, or in such places where the 

 upper or under surface of a stratum being exposed to the view 

 of the observer, admits of the immediate application of one of 

 the different kinds of clinometers well known to geologists. In 

 high mountain-chains, the real direction and inclination of the 

 strata can only be concluded from the examination of the posi- 

 tions of those lines which the seams of the strata form upon the 

 face of abrupt and precipitous rocks> often inaccessible to the 

 most hardy mountaineer. In such cases, the inexperienced ob- 

 server, who would be tempted to consider the dip of those lines 



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