ILLUSTRATIONS. 



Plate I. Landscape looking westward across the upper portion of Nai'ragansett Bay, in the 

 lowland of the Carboniferous area, to the base-leveled area of mainly crystalline 



and pre-Carboniferous rocks 7 



II. Pre-Carboniferous rocks at western border, near Providence, Rhode Island '. . . 126 



III. Plant-bearing outcrop of Wamsutta group in North Attleboro, Massachusetts 146 



IV. Faulted diabase dikes in North Attleboro, Massachusetts 152 



V. Rocky Hill, Providence, Rhode Island, a glaciated ridge of the Carboniferous 162 



VI. Carboniferous sandstones at Silver Spring, Rhode Island 166 



VII. Carboniferous sandstones near Attleboro, Massachusetts 176 



VIII. Medium-sized conglomerate, Attleboro, Massachusetts 176 



IX. Ripple-marked vertical sandstones, Attleboro, Massachusetts 178 



X. Raindrop imprints on vertical strata, Attleboro, Massachusetts 178 



XI. Plainville Valley, Wrentham, Massachusetts 180 



XII. Vertical bed of Dighton conglomerate at Attleboro, Massachusetts 184 



XIII. Near view of Dightou conglomerate, Attleboro, Massachusetts 184 



XIV. Selected waterworn and indented pebbles from Dighton conglomerate, Attleboro, 



Massachusetts 186 



XV. Vertical Carboniferous sandstones, Plainville, Massachusetts 186 



XVI. General view of surface at West Mansfield, Massachusetts 188 



XVII. Geological map of the northern and eastern portions of the Narragansett Basin 210 



XVIII. Contact of pegmatites with Kingstown shales, Watsons Pier, Rhode Island 242 



XIX. Coarse pegmatites of Watsons Pier, Rhode Island 244 



XX. Cross-stratification in pebbly sandstone of Kingstown series, Devils Foot Ledge, Rhode 



Island 248 



XXI. Sandstone-gneiss of Kingstown series, Devils Foot Ledge, Rhode Island 334 



XXII. Stratification and slaty cleavage, Aquidneck shales, eastern shore of Prudence Island.. 350 



XXIII. Wave-cut bench in Aquidneck shales, western shore of Prudence Island 352 



XXIV. Fretwork weathering of Aquidneck shales, Prudence Island 362 



XXV. Pegmatite dikes cutting Kingstown shales, Watsons Pier, Rhode Island 376 



XXVI. Hoppin Hill, a granite mass surrounded by Cambrian, North Attleboro, Massachusetts. 384 



XXVII. Sketch map of the North Attleboro Cambriau localities 386 



XXVIII. Sections in the Narragansett Bay region 3,94 



XXIX. Sections in the Narragansett Bay region 394 



XXX. Sections in the Narragansett Bay region 394 



XXXI. Geological map of the southern part of the Narragansett Basin 394 



Fit;. 1. Diagram of assumed conditions of compressive straiu in rocks in a basin of accumu- 

 lation 19 



2. Theoretical plan of the great folds of the Narragansett Basin 27 



3. Diagram showing misleading synclinal exposures of similar strata 102 



4. Exposure of disconnected dike in Lime Rock quarries, Rhode Island 108 



5. Sketch map of distribution of upper Cambrian pebbles 110 



6. Map showing distribution of metamorphosed Carboniferous rocks 120 



XIII 



