KmOSTOWN SERIES ON HOPE ISLAND. 341 



Head and inci^easing toward Eound Swamp and beyond be excluded, a 

 low general eastward dip of a series of strata, subjected to abundant sub- 

 sidiary folding, pitching southeastward along their southern border, is the 

 only explanation that occurs to the writer, and very much more field work 

 is necessary to form anything like a safe opinion on this point. In the 

 absence of more accurate information an estimate of the maximum thick- 

 ness of the strata involved in the northern Conanicut complex seems unwar- 

 ranted. The thickness certainly amounts to as much as 1,735 feet, but it 

 may many times exceed this. 



Hope Island — Litliologically the rocks forming Hope Island resemble the 

 strata exposed on the western shore of the bay more closely than the more 

 northern exposures along the western side of northern Conanicut This 

 may be due in part to the greater metamorphism of the Hope Island rocks. 

 The sandstone here is often quartzitic, of white color, and contains 

 biotitic mica. The interbedded fine-grained sandstones are usually very 

 black. Black shales are found only along the western and northern sides 

 of the island, and form evidently the lower beds of the small section here 

 involved. The quartzitic sandstones contain scattered pebbles and thin 

 conglomeratic layers. Conglomerates are present to a certain degree in 

 all the sandstone layers. On the western side of the island they are a minor 

 featn.re, while on the eastern side they form half the rock. The pebbles 

 are uniformly small, usually not over IJ inches in diameter. Many of 

 them are decidedly quartzitic or granitic. There has been little flattening 

 of the' pebbles by shearing. The strike over the southern three-fourths of 

 the island averages N. 30^ E., with an easterly dip of 60^ to 80^ on the 

 western side, and a dip of 30^ to 45^ E. on the eastern shore. These 

 strikes also suggest that the Hope Island section may underlie the exposures 

 on the westei-n shore of northern Conanicut, notwithstanding the northerly 

 strikes of the latter. The section exposed on the island is estimated to have 

 a thickness of at least 800 feet. 



At the northern end of Hope Island the dip of the strata is very low 

 to the northeastward. Were it not for this fact the more southern strikes 

 would carry these strata approximately toward Pine Hill and Gull points, 

 on northern Prudence Island. The outlines of the coast and the trends of 

 the main hills on northern Prudence Island and on Patience Island suggest 



