Page:A Treatise on Geology, volume 1.djvu/169

 CHAP. VI. and thus appear to teach us that the elevatory action, whatever might be its first violence, was continually exerted in the same localities, late into the secondary period.



The surface of the earth has, however, undergone since so many changes, that it is difficult to say how far this argument can be safely trusted. Another highly interesting problem arises out of the admission that all the displacements of rocks, previously noticed, were nearly contemporaneous: they are found to be all raised on axes nearly parallel to a line from S. W. to N. E.; and it is required to be determined whether this proximate parallelism of contemporaneous axes of elevation is a general law of the phenomena. M. E. de Beaumont is the geologist who has most strenuously advocated the affirmative of this question; but it is certain that more rigorous investigations are needed on the subject, before any physical theory, like Mr. Hopkins's ingenious view, can be safely applied to the data. It is extremely difficult to assure ourselves that the elevations above noticed, as on parallel axes, were really contemporaneous, or even very quickly succeeding, because nothing can be more complete than our ignorance of the duration of past geological periods; and, in order to render the explanation of such parallelism consistent with Mr. Hopkins's demonstrations, the occurrence of parallel elevation must be really synchronous.

The elevations on the continent of Europe of or about this ancient period (anterior to the formation of the carboniferous rocks) are located in Brittany, the Harz, the Hundsrück, the Eifel, the Ardennes.

Whence came the materials of the great mass of deposits which rest upon the primary gneiss and mica schist?