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