ILLUSTRATIONS 



Page. 



Plate II. Pre-Carbouiferous rocks at western border, near Providence, Rhode Island 120 



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 181 



XIII. Near view of Dighton 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 



FlS. 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 



7. Map showing general outline of the Narragansett Basin _ 121 



8. Section across eastern arm of the basin _ _ 122 



9. Outline map and general cross section of the northern part of the basin 123 



10. Edward Hitchcock's cross seetiou of the Carboniferous area 123 



11. Map showing distribution of red sediments 142 



12. Geological section northward from Robinson Hill _ 145 



13. Diagram showing disappearance of Wamsutta group in the Coal Measures 148 



14. Section through felsite knob in Attleboro, Massachusetts _ 153 



15. Geological section in the Millers River region 156 



16. Geological section in the Arnolds Mills region 157 



17. Hypothetical geological section east and west through Providence, Rhode Island 160 



18. Folded and faulted Carboniferous shales at Pawtucket, Rhode Island 162 



19. Sketch of zone of excessively jointed sandstones, face of McCormiek's quarry 166 



20. Geological section from Watchemocket Cove to Riverside, Rhode Island 166 



21. Geological section through rocky islets at Halsey Farm, Silver Spring, Rhode Island .. 167 



22. Geological section of rocky headland near Silver Spring, Rhode Island 168 



23. Theoretical section of folded structure on western margin of the Narragansett Basin.. 169 



24. Contemporaneous erosion with unconformity in the Carboniferous at Attleboro, 



Massachusetts 176 



25. Diagram showing cross bedding 178 



26. Geological section of Plainville Valley and thrust plane 183 



27. Section of the Mansfield Coal Measures 190 



28. Geological section in Westville, Massachusetts 199 



29. Diagram illustrating the case where boring affords a satisfactory test for coal beds 208 



30. Diagram illustrating the case where trenching affords a satisfactory test for coal 208 



MON XXXIII 7 



97 



