392 



GEOLOGICAL PHENOMENA. 



CHAPTER 

 XXVI a. 



IntTudpil 



ipieous 



rocks. 



into, and formed, this chain anterior to the accumula- 

 tion of the Permian deposits. As the latter have not 

 been observed on its eastern flank, we may be permitted 

 to surmise, that in those early periods a large portion of 

 Siberia adjacent to the Ural was also raised from beneath 

 the sea, and put without the reach of these waters, un- 

 der which the upper sands and their associated marine 

 animals were accumulated." 



The geological phenomena of the great Ural system 

 are of the most remarkable description. The strata ap- 

 pear, in some cases, highlj' metamorphosed by the subse- 

 quent action of heat ; in other cases, they ai'e dislocated 

 and intermingled with intrusive igneous rocks, broken up, 

 and thrown about in the most irregular manner, and even 

 in some remarkable cases, completely inverted. It is ob- 

 vious, indeed, that no single theory will sufRce to account 

 for all the geological changes discoverable by the careful 

 scientific observer in these extensive mountain systems. 

 Some of the phenomena are the result of a slow, conti- 

 nuous element of change, operating over a very long 

 I^eriod of time ; while others can only be ascribed to 

 some vast and terrible natural convulsion, in which the 

 internal fountains of molten material have forced their 

 way through the consolidated crust of the earth, break- 

 ing up and dislocating its strata, crushing it together 

 like ice flows, into the mountain ranges which remain 

 extended through many degrees, and injecting and over- 

 flowing the whole with igneous and metalliferous forma- 

 tions. It is during some of the latest changes of geolo- 

 Formatinn oi gical periods that the valuable metalliferous deposits are 

 dlS'i^"""' supposed to have been formed. "That the Uralian 

 chain," the authors of the Geology of the Ural Moun- 

 tains remark, " became auriferous during the most 

 recent disturbances liy which it was affected, and that 

 this took i)lace when its highest peaks were thrown up, 

 when its present water-shed was established, and when 

 the .syenitic granites, and other comparatively recent 

 igneous rocks were erupted along its western slopes. 



Various 

 sources of 

 change. 



