Page Frontispiece. Balanced Rock. 1. Arches National Park 6 2. Rock art in Arches National Park 11 3. Wolfe’s Bar-DX Ranch 14 4. Rock column of Arches National Park 21 5. Common types of rock folds 25 6. Common types of rock faults 26 7. Paradox basin 27 8. Geologic section across northwest end of Arches National Park 28 9. Index map of northwestern part of Arches National Park 28 10. Gravity anomalies over Salt Valley 31 11. Tilted block of rocks in Cache Valley graben 34 12. Jointed northeast flank of Salt Valley anticline 36 13. Index map 38 14. Tunnel Arch 43 15. “Baby Arch” 44 16. Broken Arch 45 17. Double Arch 47 18. Pothole Arch 48 19. Glen Canyon Group 53 20. Navajo Sandstone cliffs 54 21. Mouth of Salt Wash 55 22. Southeast end of faulted Cache Valley anticline 56 23. Faulted Seven Mile-Moab Valley anticline 58 24. Three Penguins 59 25. Moab Valley 60 26. Faulted wall of Entrada Sandstone 61 27. Park Avenue 62 28. Balanced rocks on south wall of Park Avenue 64 29. Courthouse Towers 65 30. The Three Gossips 66 31. Sheep Rock 66 32. Petrified sand dunes 67 33. “Hoodoos and goblins” 68 34. Eye of The Whale 69 35. Intricate crossbeds in Navajo Sandstone 70 36. Cove Arch and Cove of Caves 71 37. North Window 72 38. Looking southwestward through North Window 73 39. South Window 74 40.