352 GEOLOGY OF THE NAKRAGANSETT BASIN. 



to occur elsewhere in the Aquidneck shales of the neck. The clip of the 

 stratification of the shales over the middle and eastern part of the neck can 

 not be determined with certainty. Under these circumstances there is no 

 sufficient evidence from which to estimate the thickness of the Aquidneck 

 shales here exposed; 1,700 feet would appear to be a very moderate esti- 

 mate; 2,700 feet may be excessive. The low clips of the sandstone and 

 conglomerate on the western side of Bristol Neck, and the low clip of the 

 coarse conglomerate on the western side of Warren Neck, taken in connec- 

 tion with the small east-west extent of the lines of exposure of the 

 Aquidneck shale series, have caused the writer to believe that the shale 

 series was not so thick on Bristol Neck as it is farther southward, and that 

 probably the Aquidneck shales diminished in thickness in passing northward 

 from southern Aquidneck Island into Bristol Neck. 



AQUIDNECK ISLAND. 



The Aquidneck shales are typically exposed (1) in the Glen and (2) 

 in the valley south of McCurrys Point on the east side of Aquidneck, or the 

 Island of Rhode Island; also (3) in the valley east of Coggeshall Point, 

 (4) in Lawtons Valley, and (5) in various stream beds, railway cuts, and 

 shore exposures as far south as Coddington Point and in the railroad cut 

 west of Beacon Hill, both on the western side of the island. The Aquid- 

 neck shales form by far the greater part of the stratified rocks of the island. 

 They are characteristically dark blue, and usually do not show color band- 

 ing, which is also true of the Bristol Neck exposures. Thin fine-grained 

 sandstone beds occur not only in the shale series northward, but also in 

 the middle and southern part of Aquidneck, where the shale series is most 

 typically developed, so that the Conanicut shales are at one extreme lith- 

 ologically of the shale series, in presenting hardly any sandstone layers at all, 

 none of those existing being even coarse, while the eastern Prudence Island 

 and the northern Aquidneck exposures, just east of the Prudence Island 

 exposures, are at the opposite extreme, containing more or less interbeddecl 

 thin sandstone and some conglomerate layers. On Aquidneck Island thin 

 medium-grained sandstone beds occur in the shales (1) at the north end of 

 Coddington Neck and (2) along the main Newport -Bristol Ferry road a short 

 distance south of Lawtons Valley. Coarse sandstone, merging in places 

 into a very small-pebbled conglomerate, is found (3) east of the railroad 



