474 G. P. Merrill — Composition of Stony Meteorites. 



V VI 



Si0 2 _._. 45-46 43-59 



A1 2 3 3-21 ■ 5-30 



FeO 19-29 8-40 



Fe 2 3 2-03 



CaO 2-06 4-11 



MgO__ 26-86 35-62 



Na 2 1-11 0-60 



K 2 0-38 0*36 



MnO 0-65 



2 3 + Fe 2 3 0-98 



100-00 10001 



as world-making materials they are insufficient, and if we are 

 to regard our earth as an aggregate of cosmic matter, we must 

 assume that the materials were of a much' more highly sili- 

 ceous type than any that have been reaching us from space 

 within historical periods. This is presumably the proper inter- 

 pretation to be placed upon the results here shown. 



It is impossible through any process of magmatic differentia- 

 tion to derive from such materials, in even approximate propor- 

 tions, a series of rocks as widely variant and, in extremes, as 

 highly siliceous, aluminous and alkaline, as are the igneous 

 rocks of the earth. In fact, it would seem that the.y (the 

 meteorites) themselves must represent an extreme phase of 

 magmatic differentiation from a more acid magma. 



Whether we consider the meteorites that have reached us 

 within this period as but the fragmental remains of comets, or 

 whatever their origin, it is certainly not going beyond the 

 realm of legitimate hypothesis to assume that the relative pro- 

 portions of the elements which go to make up the mineral 

 matter in these various bodies in remote space, may vary 

 widely; that the earth to-day, in its course, is but passing 

 through* and receiving from space a deposit of materials 

 rejDresenting one and the same original body, and that body 

 one of an exceedingly basic nature, not necessarily resembling, 

 in percentage composition, the materials which may have 

 reached us during past and earlier stages of earth history^ 



* " Meteoriten und Planetoiden sind daher die voriibergehenden Zeugen 

 einer voriibergegangenen Episode in der Geschichte nnseres Planetensystems." 

 Ed. Suess. Ueber Einzelheiten in der Beschaffenheit einiger Himmelskor- 

 per, Sitz. kais. Akad. der Wiss., vol. cxvi, 1907. 



