FIGURES
[FRONTISPIECE. Aerial photograph of Denver.] [1. Index map] 3 [a]2-3. Maps showing:] [2. Physical divisions of the United States and maximum extent of the continental ice sheets] 6 [3. The Great Plains province and its sections] 8 [4. Photograph of Mescalero escarpment and southern High Plains] 9 [5. Geologic time chart] 12 [a]6-8. Maps showing:] [6. Paleogeography of U.S. in Late Cretaceous] 14 [7. Structural setting of the Great Plains] 14 [8. Progressive southward expansion of areas of deposition] 17 [9. Photograph of Big Horn strip mine at Acme, Wyo.] 18 [10. Black Hills diagram] 21 [a]11-16. Photographs showing:] [11. Weathering of granite at Sylvan Lake in the Black Hills] 22 [12. Capulin Mountain National Monument, N. Mex.] 24 [13. Mesa de Maya, Colo.] 25 [14. Spanish Peaks, Colo.] 26 [15. “The Gangplank,” Wyo.] 27 [16. Scotts Bluff National Monument, Nebr.] 28 [17. Aerial photograph of the Nebraska Sand Hills] 30 [18. Map of the Nebraska Sand Hills] 31 [a]19-30. Photographs showing:] [19. Loess plain in Nebraska] 32 [20. Ground moraine on the Coteau du Missouri in North Dakota] 34 [21. Slump blocks in North Unit of Theodore Roosevelt National Memorial Park, N. Dak.] 36 [22. Highwood Mountains, Mont.] 37 [23. Devils Tower National Monument, Wyo.] 38 [24. Glaciated valley in Crazy Mountains, Mont.] 39 [25. Powder River Basin in vicinity of Tongue River] 40 [26. Badlands National Monument, S. Dak.] 41 [27. Badlands of Little Missouri River in South Unit of Theodore Roosevelt National Memorial Park, N. Dak.] 42 [28. Hogback ridges along the Front Range, Colo.] 43 [29. Pawnee Buttes, Colo.] 44 [30. Edwards Plateau, Tex.] 47