Reviews 



SUMMARIES OF PRE-CAMBRIAN LITERATURE FOR 1902-1903. I. 



[Continued frotn Vol. X, p, Qi3.^ 



C. K. Leith. 



Arthur Keith. " Description of the Cranberry Quadrangle of North Caro- 

 lina and Tennessee." Geologic Atlas of the U. S., Cranberry Folio, No. 

 go, U. S. Geological Survey, 1903, pp. 1-9. 



Keith describes and maps the geology of the Cranberry quadrangle of North Caro- 

 lina and Tennessee, along the junction of the Piedmont Plateau and Blue Ridge. 

 Archsean, and doubtful Algonkian, rocks occupy all but the northwest corner of the area. 

 The Archaean rocks are mapped and described under the heads : Carolina gneiss. Roan 

 gneiss, soapstone, Cranberry granite, Blowing rock granite, and Beech granite. The 

 Carolina gneiss is the oldest rock of the ridge and consists of interbedded mica-schist 

 mica-gneiss, and fine granitoid layers. The Roan gneiss consists of hornblende- 

 gneiss, hornblende-schist, diorite, with some interbedded mica-schist and gneiss, all 

 cutting the Carolina gneiss. Soapstone, resulting from the alteration of peridotite and 

 pyroxenite, occurs in bodies closely associated with the Roan gneiss and probably of 

 the same age. The Cranberry granite is the most extensive formation in the district, 

 occurring chiefly in the mountain districts. It consists of granite and of schist derived 

 from granite, and cuts the Roan gneiss and Carolina gneiss. All of the before-named 

 rocks are cut by the Blowing rock gneiss and the Beech granite, which are considered 

 to be of the same age. 



Four formations are classed as doubtful Algonkian. These are : Linville meta- 

 diabase — an altered greenish diabase and gabbro ; Montezuma schist — a blue and 

 green epidotic schist, probably altered basal, and amygdaloidal basalt ; Flattop schist 

 — a gray and black schist, probably altered andesitic rocks ; meta-rhyolite — a grayish 

 meta-rhyolite and rhyolite porphyry. The first of these appears to be the lower part 

 of a surface flow, and the last three are of surface volcanic nature. 



T, L. Watson. " Copper-bearing Rocks of Virgilina Copper District, Virginia 

 and North Carolina." Bulletin of the Geological Society of America, Vol. 



XIII (1902), pp. 353-76. 



Watson describes the copper-bearing rocks of the Virgilina copper district of 

 Virginia and North Carolina and shows the adjacent rocks to be pre-Cambrian meta- 

 morphosed andesite associated with corresponding volcanic elastics. All are col- 

 lectively referred to as greenstones, and are thought to be similar to greenstones 

 described as occurring along the Atlantic coast region from eastern Canada to Georgia, 

 and from Alabama to the Lake Superior region. 



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