CONTEXTS. XI 



Paut III— Continued. 



Chapter VIII.— The Aquidneck shales — Continued. Page. 



Probable thickness of the shale section west of the Portsmouth syncline 353 



Lithological variations in the shale series 354 



Geological structure of the middle third of Aquidneck Island 354 



Strata probably folded 355 



Gould Island of the Middle Passage 356 



Southern third of Aquidneck Island 356 



Upper green shales of the Aquidneck series 356 



Sakonnet sandstones of the Aquidneck series west of the river 357 



Thickness of the upper green shales 357 



Thickness of the Sakonnet sandstones 35g 



Northern extension of the Aquidneck shales 358 



Equivalents of the Kingstown sandstone and Aquidneck shale series uortheast of Warren 



Neck 358 



Sakonnet sandstones on the east side of the river «_ 359 



Absence of the shale series beneath the coarse conglomerates east of the Sakonnet Eiver. .. 360 



Wedge-shaped areal distribution of the Aquidneck shale series 361 



Equivalence of the Kingstown sandstones and the Aquidneck shales 361 



Fossils of the Aquidneck shale series 363 



Chapter IX. — The Purgatory conglomerate 364 



Coarse conglomerate overlying the Aquidneck shale series 364 



Sakonnet sandstones within the Aquidneck shales, in transition to the coarse con- 

 glomerate 365 



Coarse conglomerate forming the latest Carboniferous rocks in the southern part of 



the Narragansett Basin 365 



Purgatory conglomerate as a typical exposure 365 



Identity of the Purgatory and the Sakonnet River western shore coarse conglom- 

 erate 3(6 



Possible syncline between the two western Paradise ridges of conglomerate 366 



Hanging Rock ridge, possibly the eastern side of an anticlinal fold 367 



Dips immediately east of Hanging Rock ridge 367 



Interpretation adopted 367 



Southward pitch of the great Paradise- Hanging Rock syncline 368 



Southward pitch of the Sakonnet River syncline 369 



Western coarse conglomerate exposures 369 



Possible syncline immediately west of Miantonomy Hill 369 



Possibility of two horizons of conglomerate at Jliantonomy Hill 370 



Interpretation adopted 371 



Geological position of the Newport Cliff section 371 



Portsmouth synclinal conglomerate 373 



Conglomerates of Warwick Neck and Swansea 373 



Thickness of the coarse conglomerate 373 



Fossil localities 374 



Chapter X. — The arkoses and basal conglomerates 375 



Natick arkose 375 



From Natick to Cranston 375 



Base of the Carboniferous south of Natick 376 



Probable relations between the various granites and pegmatites and the Carbon- 

 iferous beds 376 



Tiverton arkose 378 



From Steep Brook to Nannaquacket Pond 378 



South of Nannaquacket Pond 379 



Equivalence of the Tiverton arkoses to those near Natick 379 



Sachuest arkose 379 



Conanicut arkose 380 



Rose Island and Coasters Harbor Island arkose 380 



