xiv CONTENTS. 



PAGE 



in the Northern Tributaries of the Ohio, 323 ; in the Streams of Northern Pennsyl- 

 vania, 325 ; Material composing the Glacial Terraces, 325 ; such Terraces absent 

 from Streams wholly in the Unglaciated Region, 325 ; Terraces on the Ohio, 327 ; 

 on Beaver Creek, Pa., 328 ; on the Delaware, 289 ; Relation of Pot-holes in Graf- 

 ton, N. H., to Glacial Drainage, 330 ; Similar Phenomena in Lackawanna County, 

 Pa., 331 ; Remarkable Evidence of Abnormal Glacial Drainage in Dakota, 332 ; 

 Marginal Drainage in the Northwest, 334. 



CHAPTER XIV. 

 Kames 339-354 



In Andover.Mass., 339 ; Definitions, 339 ; Geikie's Description, 339 ; Relations of 

 Kames to Terminal Moraines, 340 ; Origin of, 341 ; indicate Lines of Temporary 

 Glacial Drainage, 342 ; Lines of, in New England enumerated, 343 ; Questions 

 respecting, in the Connecticut River Valley, 345 ; Possible Extent of Glacial Floods 

 in this Valley, 346 ; Relation of Sandy Plains to Kames, 348 ; Existence of Kames 

 foretold, 349 ; Overwash Gravel limited in Amount, 350 ; Abnormal Relation of 

 Kames to the Slope, 351 ; Summary, 353. 



CHAPTER XV. 

 Glacial Dams, Lakes, and Waterfalls . . . 355-406 



Rock Basins eroded by Glaciers, 355 ; Theory of the Great Lakes, 356 ; Two 

 Classes of Glacial Dams, 359 ; Kettle-holes, 359 ; Relation of, to Peat-bogs and to 

 Terminal Moraines, 360 ; Lakes formed by Permanent Obstruction of Preglacial 

 Channels, 362 ; the Formation of Waterfalls, 362 ; Temporary Lakes formed by 

 Ice Barriers, 363 ; Supposed Glacial Dam in the Ohio, at Cincinnati, 366 ; Evi- 

 dence that the Ice crossed the Ohio, 367 ; Consequences of such an Obstruction, 

 368 ; History of its Discovery, 370 ; Theory discussed by the American Associa- 

 tion for the Advancement of Science, 371 ; Theory confirmed by the Absence of 

 Terraces in Brush Creek, Ohio, 372 ; by the Terrace at Bellevue, Pa., 375 ; Diffi- 

 culty of Other Explanations, 376 ; the Occurrence of Vegetable Matter in the 

 Terraces of the Mono ngahela support the Theory, 377 ; Teazes Valley, W. Va., ex- 

 plained by the Theory, 379 ; Various Other Phenomena explained in a Similar 

 Manner, 382 ; Objections considered, 383 ; Claypole on, 386 ; Glacial Dam in the 

 Monongahela, 391 ; the Lake Ridges of Ohio and New York, 395 ; Glacial Dam 

 across the Mohawk and the St. Lawrence, 398 ; Glacial Lake in the Red River 

 Region of the North : Lake Agassiz, 401 . 



CHAPTER XVI. 

 The Loess 407-421 



Extent of the Deposit in China and North America, 407 ; Richthofen's Theory 

 of Deposition by Wind, 408 ; Difficulties of the Theory, 410 ; Characteristics of, 

 412 ; Changes of Level Necessary, 413 ; Probable Connection with Glacial Floods, 

 415 ; Supplementary Theories, 417. 



CHAPTER XVII. 



Flight of Plants and Animals during the Glacial 



Period 422-444 



Peculiar Distribution of Plants in the North Temperate Zone, 422 ; Professor 

 Asa Gray's Solution of the Problem, 424 ; more Detailed Statement by Professor 

 Gray, 425 ; Comparison of the Pacific with the Atlantic Forests, 426 ; Comparison 



