CONANICUT ISLAND. 231 



Here the pebbles of the conglomerates have been squeezed into thin 

 sheets, often several inches long and hardly more than a quarter of an 

 inch in thickness, so that it is difficult at times to recognize the conglom- 

 eratic nature of a layer if seen in a section transverse to the cleavage, while 

 along the plane of shearing the pebbles are very easily recognized. This 

 flattening of the pebbles is shown to an equal degree in the conglomerate 

 at the western base of Fox Hill, on Dutch Island, and along the more 

 northern and eastern exposures on Conanicut. 



The sandstones and shales exposed along the shore at Slocums and 

 Great ledges frequently contain garnets. These are of much larger size 

 than any found farther north on the island. Garnets in the sandstones on 

 the eastern side of Conanicut are very small, and those in the shales are 

 yet smaller. 1 



A walk around the border of the island is very instructive. The most 

 eastern coaly shale exposures are, except for their cleavage, but little affected 

 by metamorphism, and for this reason it was not difficult to find fossil ferns 

 there, while along the ledge exposures on the west the frequency of large 

 garnets, and often also of staurolites, makes the detection of fossil ferns in 

 these shales very difficult. Nevertheless, Prof. T. Nelson Dale found a 

 number of well-preserved fossil ferns somewhere along the ledge exposures, 

 in a layer of black coaly shale, hardly more than a foot thick, included 

 between shales containing* staurolite, garnets, and ottrelite. 



Staurolite was found only along the cliff exposures, but in places it 

 was very abundant. It was not seen on Dutch Island or Fox Hill. Garnets 

 were found in the shales on Dutch Island, but in some of the shales they 

 were entirely absent. In the black and coaly shales at Fox Hill they were 

 rare, although occurring in great numbers in the overlying green schists 

 south of Fox Hill. At several localities on Conanicut and Dutch islands 

 radiate aggregates of a greenish mineral are found rather abundantly in 

 this series of rocks. These aggregates are instructive in connection with 

 the exposures on Gould Island, in the northern part of Sakonnet River. 

 While the metamorphism undoubtedly increased in intensity westward, in 

 this region it did not increase regularly so as to make Fox Hill and Dutch 

 Island show more metamorphism than the cliff exposures of Conanicut. 



'On metamorphism in the Rbode Island coal basin, by T. Nelson Dale: Proc. Newport Nat. 

 Hist. Son., "Doo. 3, 1885, pp. 85-86. 



