480 PETROLOGICAL ABSTRACTS AND REVIEWS 



(2.20-5.60) which is almost wholly contained in plagioclase with 21-43 

 percent An. 



The great interest of the rocks lies in the fact that they belong to a rare 

 family supposed by Rosenbusch to be possibly co-ordinate with the alkali 

 and lime-alkali families. These are principally developed in three other 

 regions: India, S. Norway, Canada, and the Adirondacks. 



The magmatic relations to the harzburgites, norites, and diabases, 

 partly hypersthene-bearing, of Guinea and Sierra-Leone are still to be 

 determined. 



An alkali granite containing a soda amphibole is found farther north 

 surrounded by granites of non-alkaline facies. 



Ordinary biotite granites are abundant about the sources of the Niger. 



F. C. Calkins 



LouGHLiN, G. F. "Intrusive Granites and Associated Metamorphic 

 Sediments in Southwestern Rhode Island," Am. Jour. Sci., 

 4th ser., 1910, XXIX, 447-57. Maps 2. 



From his studies in southeastern Connecticut and southwestern Rhode 

 Island, the author became convinced that all of the granites of that area 

 are parts of one batholith, not of pre-Cambrian age, but intrusive into 

 rocks which have been mapped as Carboniferous. In a former paper, 

 not yet published, a detailed report was made of the Connecticut area. 

 The present paper gives the results of a continuation of the work eastward 

 into Rhode Island. 



In the Connecticut area the granites, which the writer calls the Sterling 

 granite series, include normal biotite granite, porph}'ritic biotite granite, 

 and alaskite; the latter cutting the other two varieties. All are intrusive 

 into the sedimentary series. In the Rhode Island area the same rocks are 

 found, supplemented by a later intrusion, represented by the granite found 

 at Westerly, R.I. Both the sediments and the Sterling granite are cut by 

 dikes of the Westerly granite, which differs from the Sterling granite only 

 in containing a higher percentage of plagioclase. 



The author concludes: (i) The Westerly granite is closely related to 

 the Sterling granite and is considered its latest exposed phase. (2) The 

 Sterling granite batholith is continuous from eastern Connecticut to Narra- 

 gansett Bay, R.I., and includes granite formerly thought to be pre-Cambrian. 

 There are no pre-Cambrian rocks in Rhode Island south of the Washington- 

 Kent county line. (3) The Sterling granite is intrusive into all the sediments 

 with which it is in contact, and its intrusion accompanied metamorphism 



