RED PRIMARY SANDSTONE. 335 



without the intervention of schist sometimes it 

 \vould appear, from the action of the weather, 

 and, at others, in consequence of a slender mica- 

 ceous lamina ; in which cases they often resem- 

 ble the laminar, or schistose sandstones of the 

 secondary class. 



These strata, like those of gneiss, are in many 

 places subject to flexure and contortion ; and 

 where these flexures are sudden and considerable, 

 it is not unusual for the stratified disposition to 

 vanish entirely, and in such a manner as -to per- 

 mit a gradation to be traced from the most shape- 

 less and fractured mass to the most regular strati- 

 fication. In such cases, the shapeless mass is 

 broken or divided into very irregular angular 

 portions ; but the more regular strata are com- 

 monly split into prismatic and cuboidal masses 

 like granite, and, when the angles have been 

 rounded by exposure, scarcely to be distinguished 

 from them at a distance. The only other cir- 

 cumstance of internal structure deserving notice 

 in this rock, is an indulation on the surfaces of 

 the beds, which is also known to occur in the 



