ROCKS OF THE REGION 



135 



There are also quartz veins in the granite and porphyry and in the 

 gabbro in connection with granite dikes. 



Recapitulating, the various rocks found in the mountains are shown 

 in the following table: 



Formation. 



Character of the rocks. 



Age. 



Red beds 



Geronimo series 



Dike rocks 



Quartz veins. . . 

 Quana granite.. . 



Rainy Mountain 

 limestone. 



Blue Creek series. . . 



Carroll ton Mountain 

 porphyry. 



Raggedy Mountain 

 gabbo. 



Sandstone and shales , 



Sandstone conglomerate, shales, and lime- 

 stones ; carries asphaltum. 



Fine-grained greenstones of various types . 



Cut by dikes . . 



Eruptive through earlier formations and 

 furnishing debris to the Geronimo 

 series. 



Blue and gray limestone folded and meta- 

 morphosed by the granite ; conformable 

 on the earlier sediments. 



Conglomerates, quartzites, sandstones, 

 running up without break into the 

 Rainy Mountain limestone and uncon- 

 formable on the earlier rocks. 



Including rhyolites, amygdaloids, and 

 some tuffs. The Saddle Mountain por- 

 phyry, of slightly different type, proba- 

 bly belongs here. 



Including a considerable variet}^ of basic 

 rocks here regarded as facies of one 

 magma. Possibly eruptive through the 

 porphyry, but not certainly so. 



Permian. 

 ? ? 



May be later. 



May be in part 

 earlier. 



Ordovician. 



Cambrian. 



Archean (?) 



Archean (?) 



Crystalline Rocks 



CLASSIFICATION 



As has already been stated, the central core of the mountains consists 

 of crystalline rocks. These include three well marked and usually easily 

 distinguished types : (a) granite, (6) porphyry, (c) gabbro. There are 

 also quartz veins and greenstone dikes. There has as yet been no oppor- 

 tunity to make microscopic studies of these rocks, but there is no reason 

 to believe them greatly different from the rocks examined by Spencer* 



*Amer. Geologist, July, 1899, pp. 47, 4S. 

 XIX— Bum,. Geol. Soc. Am., Vol. 11, 1899 



