300. GEOLOGY OF THE NARRAGANSETT BASIN. 



On the west side of the Woods Castle-Black Point anticline the series in 

 the Hanging Rocks Valley is evidently somewhat overturned in places, 

 although the chief ridge, that of the Hanging Rocks, dips 80° W. The 

 result of the more accentuated folding, as indicated by the steeper dips, is 

 a violent contortion of the rocks, shown by the local rapid variation of dip, 

 due to local folding subsidiary to the more general synclinal folding which 

 determined the great structural features of the Carboniferous area along 

 the Hanging Rock Valley and westward. This syncline is believed to 

 pitch strongly southward. 



The most northern outcrops of coarse conglomerate occur a little over 

 a mile from both Black Point and Taggarts Ferry, about three-quarters of 

 a mile west of the Sakonnet River, along the west and east sides of the 

 road. Here the strike is N. 3° E., dip 45° W., on the east side of the 

 road southward, changing to strike N. 15° E., dip 40° E., on the west side 

 of the road near the middle exposure, and dipping the same amount east at a 

 continuation of the middle exposure northward on the east side of the 

 road. This seems to represent the northern end of the syncline in the 

 coarse conglomerate bed, and lies about 60 to 80 feet above sea level. 

 Southward the base of the syncline pitches far beneath sea level. 



PEE-CABBONIFEROUS AREA. 



Between the eastern ridge of the Paradise conglomerates and the 

 Hanging Rock ridge of conglomerate lies an area of igneous rock and of 

 quartzite-schists which seems to be pre-Carboniferous. The most south- 

 western exposure of the hornblendic rock, possibly at the time of its injection 

 a coarse diabase, is found along the southern embankment of the reservoir, 

 at an angle near its middle line. The next exposure occurs at the northern 

 end of the reservoir, between the middle and the eastern creeks entering the 

 reservoir from that side. It there forms a ridge which can be traced north- 

 ward for about half a mile, and is evidently in line with the exposure south 

 of the reservoir. Bordering the east side of the reservoir is another, much 

 loftier and broader range of the igneous rock, almost half a mile long. 

 East of this lies a somewhat narrower ridge, at one point broken down and 

 permitting the formation of a glen between the main range of igneous rocks 

 westward and another high ridge lying to the eastward. This eastern ridge 

 lies directly west of the Hanging Rock coarse conglomerate with its over- 

 lying bluish sandstone and more greenish shah 7 variety. 



