182 



tory of rocks. That sketch must, however, be 

 brief; as an attempt to make it full, would en- 

 croach on that which is the more especial province 

 of a system of geology, and is partly rendered 

 unnecessary by the remarks which precede the 

 Synopsis of each family. 



Granite, as remarked in another place, is 

 found in contact with all the primary strata; 

 and, in some of these cases, a gradation of charac- 

 ter is to be seen at the place of junction. 



In the instance of gneiss, so accurately re- 

 sembling that rock in composition, this gradation 

 is perfect ; and thus, the strata of gneiss are often, 

 when in contact with granite, not to be distin- 

 guished from it. 



Where granite is in contact with micaceous 

 schist, this substance also often loses its character 

 fora short space, by the acquisition of felspar : but 

 astli resulting compound is gneiss, the transition, 

 in this ease> takes place through the medium of 

 that rock. In this instaneej Geologists have 

 often imagined the whole series to consist of 



