RELATIVE ABUNDANCE OF ELEMENTS. 947 



Order of abundconce of elements in meteorites and in the outer rocks of the earth. 



Nickel and sulphur are found in column 1 and not in column 2, but 

 in the latter sodium and potassium appear. Farrington suggests that 

 because iron meteorites are preserved longer than stony meteorites, and are 

 therefore more likely to be found, iron probably occupies a higher place 

 than it would if meteoric falls only were ^considered. He further suggests : 

 "The relative excess of magnesium and nickel and scarcity of aluminum 

 and calcium in meteoric as compared with terrestrial matter may be due to 

 the same cause."" 



REDISTRIBUTION OF THE CHEMICAL ELEMENTS. 



We are now prepared to consider the redistribution of the important 

 chemical elements as a joint result of the forces and agents of metamor- 

 phism, including therein for this purpose the forces and agents of denuda- 

 tion. In order to appreciate the results it is perhaps well to state the point 

 of view from which the redistribution is considered. If the distribution of 

 any element in the igneous and sedimentary rocks be compared it will be 

 found that in the latter class certain formations are deficient in a given 

 element, and correlative with this deficiency there is a surplus in some other 

 formation or formations. In other words, for any element some sedimentary 

 formations, as compared with the igneous rocks, are likely to show marked 

 deficiencies and some formations marked segregations. Where the material 

 segregated has a value to man, either in the form in which it exists in 

 nature or as furnishing the source of one of the elements, it becomes an 

 economic product. Thus in tracing out the redistribution of the elements 

 we are arriving at the genesis of various economic products. In this chap- 

 ter only the abundant elements are considered, but where an abundant 

 element may be an ore we are to that extent dealing with the genesis of ore 



"Farrington, cit, p. 394. 



