Loughlin — Granites and Metamorphic Sediments. 447 



Art. XLI. — Intrusive Granites and Associated Metamorphic 

 Sediments in Southwestern Rhode Island', by G. F. 

 Loughlin. 



Contents. 

 Introduction. 



Bibliography. 

 Resume of evidence in S. E. Connecticut. 

 Evidence at Westerly and Niantic, R. I. 

 Reconnaissance eastward to the Kingstown area. 

 The Kingstown area. 



Granite. 



Time of intrusion. 



The Kingstown sediments. 



Granite pebbles. 



Derivation and correlation of the Kingstown sediments. 

 Summary. 



Introduction. 



Studies iu southeastern Connecticut and southwestern Rhode 

 Island have convinced the writer that all the granites in this 

 area are parts of one composite batholith, and that this batholith 

 is not of pre-Cambrian age, but is intrusive into rocks that have 

 been mapped as Carboniferous. A detailed report on the 

 southeastern Connecticut portion was completed about two 

 years ago, and is awaiting publication by the United States 

 Geological Survey.* 



The present paper expresses the results of reconnaissance 

 work from the Connecticut-Rhode Island boundary eastward 

 to the vicinity of Narragansett Basin and of more detailed 

 study along the western border of the Basin — here designated 

 the Kingstown area. 



Bibliography. — The granites of the area studied have been 

 mentioned in a few publications, but their ages and structural 

 relations have seldom received close attention, especially at 

 critical points. C. T. Jackson, in 1840, mapped the granite 

 as "Primary" f and the sediments of the Narragansett Basin 

 as "transition graywackes" derived from the Primary. In 

 1899, Shaler,Woodworth, and Foerste published "The Geology 

 of the Narragansett Basin, R. I." X Shaler and Foerste, who 

 worked in the area under discussion, gave little attention to 

 the granites bordering the Basin. They regarded them as 

 Algonkian and distinct from the pegmatite dikes that cut the 

 Carboniferous strata of the Basin. The latest geological map 

 of North America § represents the granite as pre-Cambrian. 



* Contributions to Geology of Eastern Connecticut, 

 t Geol. and Agricult. Surv. of the State of R. I., 1840. 

 tU. S. Geol. Surv., Mon. XXXIII, 1899. 

 § Bailey Willis, Geol. Map of No. America, 1906. 



