BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 25, pp. 435-476 SEPTEMBER 28, 1914 



GEOLOGY OF THE DIAMOND IIILL-CUMBEELAND DISTRICT 

 IN RHODE ISLAND-MASSACHUSETTS^ 



BY CHARLES H. WARREJJ^ AND SIDNEY POWERS 



(Presented before the Society December 31, 1913) 



CONTENTS 



Page 



Introduction 436 



Previous work 438 



Location and topography 438 



Summary table of rock formations 439 



Pre-Cambrian rocks : Blackstone series 440 



Nomenclature 440 



Structure 441 



Cumberland quartzite 441 



Ash ton schists 442 



Smithfield limestone ^. 443 



Age relations 443 



Cambrian rocks 445 



Pennsvlvanian rocks 446 



Subdivisions 446 



Narragansett series 447 



Bellingham series 448 



Igneous rocks 449 



Pre-Cambrian 449 



Gabbro 449 



Cumberlandite 4r»0 



Serpentine veins 451 



Labradorite porphyry dikes 452 



Middle Devonian 452 



Quartz diorite 452 



Milford granite 454 



Joes Rock granite, porphyry, and felsite 456 



Grants Mills granite 458 



Comparison of the biotite granites 459 



Lower Pennsylvanian 461 



Diamond Hill felsite 461 



Wamsutta volcanoes 462 



Middle Pennsylvanian 463 



1 Manuscript received by the Secretary of the Society December 19, 1913. 



XXXI—ButL. Gbol. See. AM., Vol. 25, 1018 (435) 



