IjLLUu 1 IvA 1 lUiNo* 



Plate I. Landscape looking westward across the upper portion of Narragansett Bay, in the 

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



and pre-Carboniferons rocks , 7 



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



III. Plant-bearing oatcrop of Wamsutta gronp in North Attleboro, Massachusetts 146 



IV. Faulted diabase dikes in North Attleboro, Massachusetts -• 152 



V. Eooky Hill, Providence, Ehode 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 



XL Plainville Valley, Wrenthamj Massachusetts - 180 



XIL Vertical bed of Dighton conglomerate at Attleboro, Massachusetts - 184 



XIIL Near view of Dighton conglomerate, Attleboro, Massachusetts 184 



XIV. Selected waterworn and indented pebbles from Dighton conglomerate, Attleb(>ro, 



Massachusetts .-.., -.... , : 186 



XV. Vertical Carboniferous sandstones, Plainville, Massachusetts , 186 



XVL General view of surface at West Mansfield, Massachusetts 188 



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



XVIII. Contact of pegmatites with Kingstown shales, AVatsons 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 



XXL Sandstone-gneiss of Kingstown series, Devils Foot Ledge, Rhode Maud 3S4 



XXIL Stratification and slaty cleavage, Aquidneck shales, eastern shore of Prudence Island— 350 



XXIII. Wave-cut bench in Aquidneck shales, we&tern shore of Prudence Island - - - • 352 



XXIV. Fretwork weathering of Aquidneck shales, Prudence Island - . , 3® 



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 Cambrian localities 386 



XXVIIL Sections in the Narragansett Bay region - 394 



XXIX. Sections in the Narragansett Bay region ....-...-...,.. -.-.. - 894 



XXX, Sections in the Narragansett Bay region - 894 



XXXL Geological map of the southern part of the Narragansett Basin 394 



Fig. 1. Diagram of assumed conditions of compressive strain 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 exposwes 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 



