340 GEOLOGY OF THE I>rAREAGANSETT BASIN. 



Probable folding m the northern part of Conamcut Island TllO difficilltlOS 01 the prOblBlTL 



may be briefly stated as follows: The green bhales of the soixthern half of 

 Coiianicut make their first appearance at the southern end of the lagoon 

 east of Beaver'^Head. From this point they extend in a direction N 37° E. 

 to the eastern shore of the island, being last seen at a point a mile north of 

 Freebodys Hill. The highest layer of conglomerate at Beaver Head occurs 

 a Kttle above low-water mark on the extreme western shore of the head- 

 land. The next most eastern exposure of conglomerate northward lies 

 along the most western part of the shore of Conanicut, northwest of Round 

 Swamp. The second locality lies about N. 10° E. from the first. The 

 average strike of the sandstones, coaly shales, and conglomerate beds on 

 the western side of northern Conanicut is not more than N. 10° E., which 

 seems to suggest a connection between the Beaver Head conglomerate and 

 the conglomerates farther northward. In that ^ase, however, there is a 

 divergence of about 27° between the conglomerate layers on the west and 

 the green shales on the east, which suggests a thickening of the intervening 

 strata northward, an unconformity, a peculiar foi^m of fan-shaped folding, 

 or a fault Thei^e is, however, no good geological evidence for any one of 

 these suggestions. 



Curiously enough, the strikes on the eastern side of Conanicut, north 

 of the latitude of southern Gould Island, are also N. 10° E. This makes it 

 difficult to imagine the precise nature of a system of folding which would 

 give such an increase of area in an east-west direction northward as 

 has been just described, and which nevertheless could escape detection in 

 the i-egions where actual exposures occur. The strata on the western shore 

 of northern Conanicut dip eastward at a low angle. On the eastern shore, 

 north of the latitude of southern Grould Island, the dips appear very varia- 

 ble, being sometimes almost vertical. These steep dips may be an expres- 

 sion of that folding which must also obtain over the middle length of the 

 island, in order to reconcile the apparent divergence of the conglomerate 

 layers and the green shales as described above, without recognizing a 

 marked increase in the thickness of the strata involved or any possibility of 

 faulting or of an unconformity. The facts observed elsewhere in the field 

 do not warrant the assumption of a great unconformity here, but the possi- 

 bility of faulting must not be precluded. 



If the possibility of a fault starting somewhere northeast of Beaver 



