CHAPTER X.

The Date of the Glacial Period 332-364

Appendix on the Tertiary Man 365-374

Index 375-385

LIST OF ILLUSTRATIONS.

FIG. PAGE

1. Zermatt Glacier 2 2. Formation of veined structure 3 3, 4. Formation of marginal fissures and veins 4 5. Fissures and seracs 4 6. Section across glacial valley, showing old lateral moraines 5 7. Mont Blanc glacier region 10 8. Svartisen Glacier 13 9. Floating berg 18 10. Iceberg in the Antarctic Ocean 20 11. Map of southeastern Alaska 22 12. Map of Glacier Bay, Alaska 25 13. Front of Muir Glacier 26 14. Map of glaciers in the St. Elias Alps 31 15. Map of Greenland 33 16. Diagram showing the character of glacial motion 43 17. Line of most rapid glacial motion 45 18. Diagram showing retardation of the bottom of a glacier 46 19. Bed-rock scored with glacial marks 52 20. Scratched stone from the till of Boston 54 21. Typical section of till in Seattle, Wash. 55 22. Ideal section showing how the till overlies the stratified rocks 56 23. Vessel Rock, a glacial boulder 56 24. Map of Rhône Glacier 58 25. Conglomerate boulder found in Boone County, Ky. 63 26. Mohegan Rock 72 27. Drumlins in Goffstown, N. H. 73 28. Map of drumlins in the vicinity of Boston 75 29. Section of kame 77 30. Map of kames in Andover, Mass. 78 31. Longitudinal kames near Hingham, Mass. 79 32. Map showing the kames of Maine and southeastern New Hampshire 81 33. Western face of the Kettle Moraine near Eagle, Wis. 99 34. Section of the east-and-west glacial furrows on Kelly's Island 103 35. Same as the preceding 105 36. Section of till near Germantown, Ohio 108 37. Moraines of Grape Creek, Col. 123 38. Map of North America in the Ice period 127 39. Quartzite boulder on Mont Lachat 128 40. Map showing glaciated areas in North America and Europe 130 41. Maps showing lines of _débris_ extending from the Alps into the plains of the Po 134 42. Section of the Cefn Cave 148 43. Map showing moraine between Speeton and Flamborough 156 44. Diagram-section near Cromer 166 45. Section through the westerly chalk bluff at Trimingham, Norfolk 162 46. Section across Wales 172 47. Section of cliff at Flamborough Head 176 48. Enlarged section of the shelly sand and surrounding clay at _B_ in preceding figure 177 49. Map showing the glaciated area of Europe 184 50. Map showing old channel and mouth of the Hudson 195 51. New York Harbor in preglacial times 197 52. Section across the valley of the Cuyahoga River 200 53. Map of Mississippi River from Fort Snelling to Minneapolis 209 54. Map showing the effect of the glacial dam at Cincinnati 213 55. Map of Lake Erie-Ontario 219 56. Map of Cuyahoga Lake 221 57. Section of the lake ridges near Sandusky, Ohio 223 58. Map showing stages of recession of the ice in Minnesota 225 59. Glacial terrace on Raccoon Creek, in Ohio 227 60. Ideal section across a river-bed in drift region 229 61. Map of Lakes Bonneville and Lahontan 234 62. Parallel roads of Glen Roy 239 63. Map showing glacial terraces on the Delaware and Schuylkill Rivers 243 64. Palæolith found by Abbott in New Jersey 244 65. Section across the Delaware River at Trenton, N. J. 245 66. Section of the Trenton gravel 246 67. Face view of argillite implement found by Dr. C. C. Abbott in 1876. 247 68. Argillite implement found by Dr. C. C. Abbott, March, 1879 248 69. Chipped pebble of black chert found by Dr. C. L. Metz, October, 1885 249 70. Map showing glaciated area in Ohio 250 71. Palæoliths from Newcomerstown and Amiens (face view) 252 72. Edge view of the preceding 253 73. Section across the Mississippi Valley at Little Falls, Minn. 254 74. Quartz implement found by Miss F. E. Babbitt, 1878, at Little Falls, Minn 255 75. Argillite implement found by H. T. Cresson, 1887 259 76. General view of Baltimore and Ohio Railroad cut, Claymont, Del. 260 77. Section across valley of the Somme 262 78. Mouth of Kent's Hole 268 79. Engis skull (reduced) 274 80. Comparison of forms of skulls 276 81. Skull of the Man of Spy 277 82. Tooth of Machairodus neogæus 281 83. Perfect tooth of an Elephas 281 84. Skull of Hyena spelæa 282 85. Celebrated skeleton of mammoth in St. Petersburg Museum 283 86. Molar tooth of mammoth 284 87. Tooth of Mastodon Americanus 284 88. Skeleton of Mastodon Americanus 286 89. Skeleton of Rhinoceros tichorhinus 287 90. Skull of cave-bear 287 91. Skeleton of the Irish elk 288 92. Musk-sheep 289 93. Reindeer 290 94. Section across Table Mountain, Tuolumne County, Cal. 294 95. Calaveras skull 295 96. Three views of Nampa image, drawn to scale 298 97. Map showing Pocatello, Nampa, and the valley of Snake River 299 98. Section across the channel of the Stanislaus River 300 99. Diagram showing effect of precession 308 100. Map showing course of currents in the Atlantic Ocean 314 101. Map showing how the land clusters about the north pole 319 102. Diagram showing oscillations of land-surface and ice-surface during the Glacial epoch 323 103. Diagram of eccentricity and precession 333 104. Map of the Niagara River below the Falls 334 105. Section of strata along the Niagara Gorge 336 106. Map showing the recession of the Horseshoe Falls since 1842 338 107. Section of kettle-hole near Pomp's Pond, Andover, Mass. 345 108. Flint-flakes collected by Abbé Bourgeois 368

MAPS.

TO FACE PAGE

Contour and glacial map of the British Isles _Frontispiece._

Map showing the glacial geology of the United States 66

Map of glacial movements in France and Switzerland 132

MAN AND THE GLACIAL PERIOD.