18 M. Molis''s Summary of Gao^nostical Fhenomena. 



expression, when it is stratified. It is found in a similar 

 way in the various slaty mountain masses, and there pre- 

 sents very remarkable relations. It has been supposed, 

 that the limestones lying next the central mass (what are 

 termed primitive limestones) possess the most distinct, and 

 frequently a large granular structure ; those more remote 

 (what are termed transition limestones) a less distinct struc- 

 ture, at least one which is less coarsely granular ; and the se- 

 condai-y limestones, to speak generally, more of an earthy com- 

 position ; and there are undoubtedly very many examples which 

 countenance such an opinion. But nevertheless, the pheno- 

 menon is not one of universal occurrence, and, even in masses 

 which are connected together, all these diiferences of structure 

 present themselves next one another. It would, therefore, be 

 a fallacious mode of proceeding, to take the size of the grains 

 of the limestone as the test of its geognostical distance from 

 the central mass, a distance which can only be determined by 

 superposition. 



Limestone occurs partly in pretty regular beds, partly in 

 irregular masses, both of which have very various dimensions, 

 — the first being sometimes of almost inconceivable extent. 

 They seem to increase in thickness and extent as their dis- 

 tance increases from the central masses, or, where such do 

 not exist, from the central chain ; and they, as it were, ac- 

 quire one of the chief characteristics of the slate-rocks, inas- 

 much as they generally form on both sides of the central 

 chain, a peculiarly long and high chain, in which again many 

 mountain masses are contained in the same, and not unfre- 

 quently, very remai'kable manner, as the slate series includes 

 porphyry, syenite, and some other mountain rocks. 



Beds ami k^eins. — The beds of granite, porphyry, syenite, 

 greenstone, limestone, &c., which occur in the slate-rocks, 

 and which are generally conformable to their structure on the 

 small and on the large scale, nevertheless very frequently cut 

 this structure at some places, thus proving directly that it is 

 not stratification ; for true stratification can be cut by no bed, 

 which itself must be regarded as a stratum possessing parti- 

 cular characters, — as directly follows from the idea of stratifi- 

 cation. It follows from this phenomenon, that beds of this 



