CHAPTER V.

THE WORK OF SNOW AND ICE.

+Snow- and Ice-fields+ 244

The passage of snow into névé and ice, 246. Structure of the

ice, 247. Texture, 247. Inauguration of movement, 248.

+Types of Glaciers+ 251

+The General Phenomena of Glaciers+ 256

Dimensions, 256. Limits, 258. Movement, 259. Conditions

affecting rate of movement, 261. Likenesses and unlikenesses

of glaciers and rivers, 262.

+Surface Features+ 266

Topography, 266. Surface moraines, 266. Relief due to surface

débris, 268. Dust-wells, 269. Débris below the surface, 272.

+Temperature, Waste, and Drainage+ 273

The winter wave, 274. The summer wave, 276. The temperature

of the bottom, 276. Temperature of the interior of the

ice, 277. Compression and friction as causes of heat,

278. Summary, 279. Movement under low temperature, 279.

Evaporation, 279. Drainage, 280.

+The Work of Glaciers+ 281

_Erosion and Transportation_ 281

Getting load, 282. Conditions influencing rate of erosion,

283. Summary, 286. Varied nature of glacial débris, 286. The

topographic effects of glacial erosion, 287. Fiords, 290. The

positions in which débris is carried, 290. Transfers of load,

292. Wear of drift in transit, 298.

_Deposition of the Drift_ 298

Beneath the body of the ice, 298. At ends and edges of

glaciers, 299.

+Types of Moraines+ 301

The terminal moraine, 301. The ground moraine, 301. The

lateral moraines, 302. Distinctive nature of glacial

deposits, 304. Glaciated rock surfaces, 304.

+Glacio-Fluvial Work+ 305

+Icebergs+ 307

+The Intimate Structure and the Movement of Glaciers+ 308

The growth and constitution of a glacier, 308. The

arrangement of the crystal axes, 312.

_The Probable Fundamental Element in Glacial Motion_ 313

Melting and freezing, 313. Accumulated motion in the terminal

part of a glacier, 316.

_Auxiliary Elements_ 317

Shearing, 317. High temperature and water, 318. Applications,

319.

_Corroborative Phenomena_ 320

_Other Views of Glacier Motion_ 321

Geology, Vol. 1 [of 3] · 第 5 / 22 章