510 Geology and Magnetism. 



According to Von Buch and other continental geologists, the 

 directions of the lamination of the crystalline rocks in Sweden and 

 Finland are from south to north, varying occasionlly towards the 

 east. In Mexico the laminated structure is principally towards the 

 north-west ; but in the plains it is frequently found due north 

 and north-east. In the United States its general direction is simi- 

 lar to that of South America, i. e. from south to north, but present- 

 ing numerous contortions, and thus causing local variations in the 

 direction, either towards the east or west, according to the nature 

 of the local resistance. 



" The direction of primitive and transition beds" (gneiss and 

 schist), says Humboldt, " is not a trifling phenomenon of the locali- 

 ty, but, on the contrary, a phenomenon independent of the direc- 

 tion of secondary chains, their branchings, and the sinuosity of 

 their valleys ; a phenomenon of which the cause has acted, at 

 immense distances, in a uniform manner, for instance in the an- 

 cient continent, between the 43° and 57° of latitude, from Scotland 

 as far as the confines of Asia." 



Hence it will be observed that the universality of this structure 

 has not escaped attention. 



Dr. M'Culloch, in his description of the Western Islands of 

 Scotland, remarks on the striking uniformity of the beds of gneiss 

 and schist being more or less in a north-east direction. In cutting 

 any of these beds, as they are called, in an east and west direction, 

 i. e. from the eastern to the western coast of Scotland, the lamina 

 would be intersected transversely, and on examination the planes 

 would be found more or less vertical, sometimes leaning to the east 

 and sometimes to the west : any east and west section of consider- 

 able length would be found the same. It must be understood, 

 however, that the above remark is confined to the average, because 

 numerous bends and contortions of very considerable extent are 

 frequent in this fundamental structure, and are susceptible of con- 

 stant changes from the effects of chemical action going on in it. 



On the eastern coast, between Waterford and Dublin, the more 

 ancient lamination presents a mean average direction towards the 

 north-east, but is also intersected at various points by a compara- 

 tively recent lamination in a north-west direction. It is at these 





