464 ORIGIN OP ERUPTIVE AND PRIMARY ROCKS. 



must have been derived from something, which something cannot 

 be assumed to be the result of a sedimentary operation." 



" In the same way there must have existed a covering through 

 which the oldest eruptive formations were protruded, and a founda- 

 tion upon which they could spread themselves out ; and the whole 

 series of eruptive rocks must, like those of sedimentary origin, have 

 at the commencement been borne by something which cannot be 

 regarded as the result of an eruptive operation." 



" We find ourselves thus obliged, from two sides, to assume the 

 existence of an originally existing solid crust of the planet, which 

 formed the theatre and the foundation for all the later formations, 

 above and beneath which those two energies in nature could de- 

 velop themselves ; through which on the one side the sedimentary, 

 and on the other side the eruptive formations were brought into 

 existence ; and that formation of which this original foundation con- 

 sisted it is consequently proper to entitle the primitive or theme- 

 lian, the original or fundamental formation." 



" To this formation those enigmatical, deepest-lying rocks belong- 

 which resemble sedimentary strata, in possessing more or less per- 

 fect stratification, and which resemble eruptive rocks, when their 

 mineral composition and their crystalline structure are taken into 

 consideration; but they are devoid of the fragmentary rocks and 

 the organic remains by which the sedimentary formations are 

 characterized, and on the other hand do not possess the veins> 

 masses and streams common to eruptive rocks, nor the abnormal 

 relations of these at their junction with other rocks. Tn a word, 

 we meet in the primitive formation many of those rocks which we 

 have above designated cryptogenous, such as gneiss, micaschist ? 

 hornblende-schist, etc. ; rocks whose unaltered character we are 

 not justified in denying in every case, merely because in some 

 cases similar rocks have been formed by the metamorphosis of 

 sedimentary strata, or in an eruptive manner. Those who, because 

 a few beds of mica-schist or gneiss have been admitted to be meta- 

 morphosed clay-slate or greywacke slate, declare that all mica- 

 schists and gneiss are only altered sedimentary rocks, only meta- 

 metamorphosed beds of mud, virtually remove the ground from 

 beneath our feet, and limit us to a transcendental succession of 

 sedimentary deposits, which, downward, has no end, or rather no 

 demonstrable commencement; because finally the actual sediment- 

 ary origin can neither be recognized nor proved, but can only be 

 maintained as a hypothetical assumption." 



