264 M. Keilhau's Theory of Granite and other Rods. 



It is quite evident that the processes which have caused the 

 formation of granite belonged especially to the clay- slate tracts ; 

 but as these every where contain masses of limestone, we find 

 that the limestone was also changed in those regions where gra- 

 nitification took place. In the same manner, in particular 

 places, the sandstone may have been transformed, together also 

 with portions of the primary strata, into which we have found 

 that transition-granite penetrates, partly as forming a passage 

 to the fundamental gneiss, and partly ramified in it. In the 

 oTanitic formations are contained several chemical constituents. 



neath the syenite at Weiubohla, between Dresden and Meissen ; these were 

 partly small, externally blackish grains of a felspathic nature (also remark- 

 ed by Professor AVeiss, but naturally with an entirely different interpreta- 

 tion), and partly small, also imbedded portions, having the aspect of wea- 

 thered, very imperfect granite. I have lately read, that at other places 

 small fragments of granite have been remarked in the stratified rocks that 

 are associated with the granites and syenites in those parts of the valley of 

 the Elbe. These localities undoubtedly merit the new investigations which 

 are perhaps now in progress, and which I am convinced will produce a rich 

 harvest for the science ; as it really seems quite acknowledged that the con- 

 nection of the groups of facts hitherto adduced cannot be at all explained. 

 (Professor Keilhau then quotes Dr Cotta's paper on the relative ages of 

 the granite and chalk in Saxony, from which we translate the following 

 passage : " Near Hohnstein small fragments of granite have been found in 

 a conglomerate-like sandstone, probably belonging to the Jura formation, 

 and which is interposed in an inclined position between granite and sand- 

 stone. These fragments, from their mineralogical characters, woidd seem 

 to have been derived from the same granite which is immediately superim- 

 posed. Thus the whole matter is rendered inexplicable ; for as, on the one 

 hide, we are irresistibly forced to regard the granite as the newer formation, 

 so, on the other, we cannot understand how fragments of this granile have 

 found their way into the subjacent sandstone, if the former be really newer 

 tlian the latter. The questions. Do these pieces of granite perhaps belong 

 to another older formation ? Or is the conglomerate-like sandstone, which 

 contains them, a product of the friction, and only fprmed by tlie elevation ? 

 seem to include the only, though much sought for, modes of solving the dif- 

 ficulty ; for the view proposed by Weiss of the dry elevation of the pre- 

 viously existing and solid granite, which may readily be placed in con- 

 nection with this phenomenon — though it is ingenious, and at first sight 

 satifrfactory — involves many difficult considerations." — Cotta in Leonkard's 

 Jahrhuch for 1836, p. 23. Dr Cotta, in his " Geognostichc Wandermigen" has 

 recently expressed an opinion favourable to the idea of the elevation of the 

 Hohnstein and Weinbohla granite in a solid .state. — Edit.) 



