1913] GeologiCx^l History of Westekis^ K. C. 37 



been subject to erosion which has brought them to their present 

 outline. 



The next formation was the lava rocks, which were poured 

 forth upon the surface of the Archean rocks. These lava flows 

 are of considerably later period than the granites and gneisses 

 and are older than the overlying Cambrian sedimentary rocks, 

 and they may belong to the Algonkian age. Some of these rocks 

 were undoubtedly of volcanic nature, the intrusions coming to 

 the surface as flows of lava and sj)reading out over the Carolina 

 and Roan gneisses and the Cranberry and Beech granites. There 

 was a very long interval between the formation of the last of 

 the Archean rocks before the volcanic activity ; and during this 

 period these old Plutonic rocks were subject to very excessive 

 erosion. This volcanic activity probably extended into the 

 Cambrian time, and many of the lava flows were probably at 

 the surface when the Cambrian strata were laid down. The 

 indication of this is the finding of sheets of basalt conglomerate 

 interstratified with the lower strata of the Cambrian. Rocks of 

 this period include meta-diabase, found just north of Linville 

 and to the east in Grandmother Gap and crossing the Yonah- 

 lossee road at several places; blue and green epidotic schists, 

 which have been probably altered from basalt, such as are to be 

 seen in the vicinity of Pineola and Montezuma, Avery County, 

 and Hanging Rock, Caldwell County; a gray and black schist 

 probably formed by the alteration of an andesitic rock, which is 

 to be observed on Flat Top Mountain and Pine Ridge, Watau- 

 ga County; and metarhyolite, such as is found on the slopes of 

 Dugger Mountain, Sampson Mountain, and in Cook's Gap, Wa- 

 tauga County. 



These Archean rocks, with the volcanic formations, were then 

 subjected to a long period of erosion, and the sea at the same 

 time encroached upon large areas of the dry land. The sedi- 

 ments deposited formed the rocks which are known as the Cam- 

 brian. Portions of the Archean rocks were submerged and at 

 times uplifted, and there was not a continuous series of these 

 sedimentary deposits. 



These sedimentary rocks, formed from the erosion of the 

 Archean and Algonkian rocks and from siliceous and calcareous 



