CHAPTER XI. 



RELATIONS OF METAMORPHISM TO THE DISTRIBUTION OF 

 THE CHEMICAL ELEMENTS. 



In consequence of metamorphism the chemical elements are redis- 

 tributed on the face of the earth. This redistribution concerns many large 

 questions of geological theory. At the present time our knowledge of 

 metamorphism is not sufficiently advanced to treat the redistribution of the 

 elements except in a very imperfect manner. In the following pages an 

 attempt is made to consider the original source of each of the important 

 chemical elements composing the outer part of the earth, and the effect which 

 the metamorphic processes have had on its redistribution and on the character 

 of the secondary rocks. So far as practicable redistribution is dealt with in a 

 quantitative way, but a quantitative treatment is necessarily subject to the 

 very imperfect hypotheses upon which it is based. Indeed, for the most 

 part the quantitative estimates are the roughest sort of approximations, made 

 more with a view of stating the various problems which in the future will 

 undoubtedly be satisfactorily treated quantitatively rather than with the 

 belief that the calculations given even approach accuracy. They are all 

 purely provisional, and it is hoped that they will be considered from this 

 point of view. Indeed, this chapter is no more than an attempt to blaze a 

 trail in the wilderness. It will require the work of many men for many 

 years to conquer the wilderness. 



COMPOSITION OF THE EITHOSPIIERE. 



The term lithosphere as used in this chapter is rigidly restricted to that 

 part of the solid crust of the earth of which we have observational knowl- 

 edge, and which, following Clarke, is assumed to extend to a depth of only 

 10 miles (16.1 kilometers) below the level of the sea. According to R. S. 

 Woodward, the volume of the part of the earth that is above the sea and 

 that extends to a depth of 10 miles (16.1 kilometers) below the level of the 



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