Figures
[1. The Connecticut River undercuts the Hadley bank] 2 [2. Natural levees south of the Sunderland Bridge] 2 [3. Block diagram showing main features of central Massachusetts at the present time] 5 [4. Block diagram showing main features of central Massachusetts during recession of the Ice Sheet] 5 [5. Block diagram showing main features of central Massachusetts during excavation of the lowland] 13 [6. Block diagram showing main features of central Massachusetts after Triassic basins were filled] 13 [7. Map of Mount Toby showing gorges filled with conglomerate] 20 [8. Map showing agglomerate burying a fault scarp on Notch power line] 24 [9. Block diagram showing main features of central Massachusetts during volcanic stage] 27 [10. Block diagram showing the Triassic basins of central Massachusetts] 27 [11. Map of old volcanic region near Mount Hitchcock and west of the Notch] 29 [12. Block diagram showing topography during formation of the lead veins] 31 [13. Block diagram of region during Middle Ordovician time] 39 [14. Block diagram of region at end of Ordovician time] 39 [15. Block diagram of region during Devonian period] 39 [16. Block diagram of region during Carboniferous period] 41 [17. Block diagram of region in early Triassic time] 41 [18. Block diagram of region in late Triassic time] 41 [19. Block diagram of region at opening of Cenozoic era] 45 [20. Block diagram of region at the present time] 45 [21. Map showing location of interesting places] 53 [22. Meander scarps at edge of flood plain, Sunderland] 57 [23. Map of the Leverett lead veins] 65 [24. Diagrams showing development of Notch and Notch Mountain] 74