186 Prof. Nepomuk Fuchs' Chemical Views regarding 



at all points on the globe ; for while granite was formed at one 

 place, syenite, porphyry, mica- slate, greenstone, and quartz- 

 rock were formed at others. We are to regard, as varieties of 

 only one formation, the members of the siliceous series, that 

 are constantly passing into one another, and more especially 

 the older and compound ones ; and we may conveniently term 

 the whole compound members of the siliceous series granitic 

 rocks (ffranitartige gehilde). The waters were sometimes at 

 rest and sometimes agitated, and this dilFerence so influenced 

 the structure and external form of the mountain masses, that 

 some were formed without a distinct stratified structure, others 

 distinctly stratified, and that some had their structure more 

 perfectly developed, and others had it less so. The waters 

 must have been particularly tranquil at first, while it was, as 

 it were, fettered by the pasty mass. It was only after a con- 

 siderable portion of the latter had been crystallized, that it ac- 

 quired more freedom, and could be set in motion by the air. 

 At a more recent period it became particularly agitated and 

 stormy, and hence the members of the siliceous series could 

 not be so perfectly and distinctly developed as before. This 

 imperfection commences in clay-slate, a rock which is nothing 

 else but a granite, with very small and indistinct component 

 parts. In the secondary rocks, the quartz presents itself only 

 in small grains, which, in the course of time, became united, 

 so as to form sandstone. The triple combinations of silica, 

 alumina, potash, &c. which, in the primary period, gave rise to 

 the different kinds of felspar and mica, occurred in the modern 

 period only as a fine mud, and formed the different varieties of 

 clay. Mica only was frequently developed in small scales in 

 the modern period, while the felspar lost its characters in a 

 friable fine-grained mass. 



Quartzose sand, sandstone, and clay very frequently, nay, al- 

 most generally, occur mixed with another, and in such rela- 

 tions, that, if circumstances had been favourable to their de- 

 velopment, they would very probably have afforded the most 

 perfect granite. Hence we may, with good reason, say, that 

 this mixture is the representative of granite in the modern 

 period ; an idea which is countenanced by the fact, that such a 

 mixture sometimes actually passes into well marked granite. 



