154 LYELL'S ELEMENTS OF GEOLOGY. 



Term Transition, why objectionable. 



been precipitated from a primeval ocean, but were sedimentary 

 strata altered by heat. In his writings, therefore, and in those 

 of his illustrator, Playfair, we find the germ of that metamorphic 

 theory which has been already expounded.* 



At length, after much controversy, the doctrine of the igneous 

 origin of trap and granite made its way into general favour ; 

 but although it was, in consequence, admitted that both granite 

 and trap had been produced at many successive periods, the term 

 primitive or primary still continued to be applied to the crystal- 

 line formations in general, whether stratified, like gneiss, or un- 

 stratified, like granite. The pupil was told that granite was a 

 primary rock, but that some granites were newer than certain 

 secondary formations ; and in conformity with the spirit of the 

 ancient language, to which the teacher was still determined to 

 adhere, a desire was naturally engendered of extenuating the 

 importance of those more modern granites which new observa- 

 tions were continually bringing to light. 



A no less decided inclination was shown to persist in the use 

 of the term "transition," after it had been proved to be almost 

 as faulty in its original application as that of flotz. The name 

 of transition, as already stated, was first given by Werner, to 

 designate a mineral character, intermediate between the meta- 

 morphic state and that of an ordinary fossiliferous rock. But 

 the term acquired also from the first a chronological import, be- 

 cause it had been appropriated to sedimentary formations, which, 

 in the Hartz and other parts of Germany, were more ancient 

 than the oldest of the secondary series, and were characterized 

 by peculiar fossil zoophytes and shells. When, therefore, geol- 

 ogists found in other districts stratified rocks occupying the same 

 position, and inclosing similar fossils, they gave to them also the 

 name of transition, according to rules which will be explained 

 in the next chapter ; yet, in many cases, such rocks were found 

 not to exhibit the same mineral texture which Werner had called 

 transition. On the contrary, many of them were not more crys- 

 talline than dhTerent members of the secondary class ; while, on 

 the other hand, these last were sometimes found to assume a 

 semi-crystalline and almost metamorphic aspect, and thus, on 

 lithological grounds, to deserve equally the name of transition. 

 So remarkably was this the case in the Swiss Alps, that certain 

 rocks, which had for years been regarded by some of the most 

 skilful disciples of Werner to be transition, were at last acknow- 

 ledged, when their relative position and fossils were better un- 

 derstood, to belong to the newest of the secondary groups ! If 



j. 



* See chapters X. and XL 



