BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 24, PP. 301-334, PLS. 7-9 JUNE 16, 1913 



PETROLOGY OF A SERIES OF IGNEOUS DIKES IN CENTRAL 

 WESTERN VIRGINIA x 



BY THOMAS L. WATSON AND JUSTUS H. CLINE 



(Presented by title before the Society December 30, 1912) 



CONTENTS 



Page 



Introduction 302 



Resume of the geology of middle western Virginia 303 



Distribution and geologic field relations of the dikes 306 



Contact metamorphism 308 



General petrology of the igneous rocks 309 



Introductory statement 309 



Granite-felsophyre (toscanose) 309 



General statement 309 



Megascopic character 309 



Microscopic character 310 



Chemical composition and classification in the quantitative system . 310. 



Quartz gabbro (tonalose ( ?) ) '. 311 



Megascopic character 311 



Microscopic character 312 



Chemical composition and classification in the quantitative system . 313 



Nepheline syenite (miaskose) 314 



Megascopic character , 314 



Microscopic character 315 



Chemical composition and classification in the quantitative system. 316 



Teschenite or analcite-basalt (monchiquose ( ?) ) 318 



Megascopic character 318 



Microscopic character 318 



Chemical composition and classification in the quantitative system . 320 



Camptonite (ourose ( ?) ) 321 



Megascopic character 321 



Microscopic character 322 



Chemical composition and classification in the quantitative system . 325 



Olivine diabase (auvergnose) 327 



Megascopic character 327 



Microscopic character 327 



Chemical composition and classification in the quantitative system . 828 



Summary and conclusions of the petrologic relations of the rock typos 329 



Introduction ' 329 



1 Manuscript received by the Secretary of the Society, February \\, 1918, 



(301 i 



