ROSS ON PARALLEL LINES OF ELEVATION. 137 



older zone), and the volcanoes themselves are in the line of zone 

 'No. 7, — the oldest of the intersecting zones. 



There is a remarkable coincidence between the prevailing zone 

 of parallel lines of elevation in any given region, and the lines of 

 equal magnetic intensity in that region. Thus in the west of North 

 America and east of Asia they coincide with zone No. 1 ; in the 

 east of North America, in Central Europe, and in the south- 

 west of Asia with zone No. 2; in the Parimean region of South 

 America, and the Kong and Komri mountain region of Africa, as 

 also in the central regions of Asia, with zone No. 3 ; in Scandinavia 

 with zone No. 4 ; in the Ural Mountains, with zone No. 6 ; and 

 on the south-eastern side of Africa and the Yabloni Mountain 

 region of Asia, with zone No. 7. 



Beaumont haS the honor of having first developed the doctrine 

 of parallel lines of elevation. His observations apply chiefly to 

 Europe, and have great merit. He classifies the lines of elevation 

 in Europe alone into nineteen systems, assigning a definite age to 

 each. It seems to me that he obtains this large number, in con- 

 sequence of two^ftiisconceptions, that were likely to occur in the 

 early study of this subject, especially in Europe, where the great 

 typical zone is not present at all to an appreciable extent. The 

 first mistake consists in his indicating the systems by ascribing to 

 them definite directions with regard to the cardinal points, and thus 

 failing to take into account the difference in this respect produced 

 by a difference in longitude ; and the second that he did not suffici- 

 ently take into account the principle of successive epochs of activity 

 along the same lines of elevation. I find, however, that he has 

 attempted a generalization which would include all the chief 

 mountain ranges of the earth, and which I give in the words of E. 

 Lambert in his *' Cours Elementaire de Geologic." 



Les lignes paralleles, considerees par M. de Beaumont, sont des arcs 

 de grands cercles du spheroide terrestre qui,' prolonges, vont toutes 

 conconrir en un point, qui serait le pole d'un autre grand cercle perpen- 

 dieulaire a ceux des systemes ; mais dans une petite etendue les arcs 

 peuvent etre consideres comme paralleles. 



M. de Beaumont considers the parallel lines to be arcs of great 

 circles of the earth which, if prolonged, would all meet in a point 



