278 



INDEX. 



Surface of a glacier moves faster than its 

 bottom, stated as probable, 24, 54-56; 

 proved by experiment, 172, etc. ; con- 

 firmed on "Glacier of the Aar, 186; favour- 

 able to the plastic theory, 187. 



Tables, glacier, 241. 



Talefre, Glacier of, 38 ; issue of ice through 

 the contracted gorge of the glacier so 

 called, 39, 142 ; its motion determined, 

 191, etc. ; veined structure, 192, 200. 



Temperature at Geneva and St. Bernard, 

 131, 224. 



Temperature, its effects on the movement 

 of glaciers, 35, 73, 138, 206, 222. 



Temperature of freezing water, 229. 



Tensions and thrusts in the interior of a 

 glacier, 149 ; vary from point to point of 

 the same glacier at different seasons, 150 ; 

 tensions and thrusts alternate, 155. 



Terminal part of a glacier moves compara- 

 tively slowly, 130, and note; its move- 

 ment in winter, 130, note, 179, 272 ; re- 

 tarded by the friction of the soil, 173. 



Theories of glacier motion, De Saussure's, 

 15, 31, 95, 249; De Charpentier's, 15, 32, 

 etc., 248. See Plastic Theory. 



Thomson, Mr. James, quoted, xiv, xxiv. 



Thomson, Mr. John, quoted, 212, note. 



Thomson, Prof. William, quoted, xiv, xxiv. 



Torrential motion of some glaciers, 147 ; 

 destroys veined structure, 24, 161-2. 



Tour, Le, Glacier and Col of, 227. 



Tyndall, Dr., quoted, xiv, etc., 228 



U, station so marked on the Mer de Glace,17l. 



V, station so marked on the Mer de Glace, 

 221. 



Veined structure of glaciers, observed by 

 the author in 1841 on the Glaciers of the 

 Aar and Rhone, 1, etc.; extends to a 

 great depth, 3; pervades glaciers from 

 the neve to their termination, 4; moat 

 developed near moraines, 5 ; endures for 

 more than one season, 5 ; the direction 

 of the veins traced over the glacier, 5, 19, 

 etc. ; produce a false appearance of hori- 

 zontal stratification of the glacier at its 

 lower end, 5; apparently perpendicular 

 to lines of greatest pressure, 6 ; structure 

 of the Glacier of the Rhone, 6 ; also per- 



?endicular to lines of fissure or crevasses, 

 , 145, 192 ; not due to stratification or 

 sedimentary deposition, 8 ; resembles 

 slaty structure of some rocks, 8, 92 ; in 

 the Glacier of La Brenva, 19 ; course of 

 the veins generally in glaciers of different 

 forms, 20 ; in glaciers of the second order, 

 21; theory of, 23; strongly developed 

 where glaciers unite, 24 ; tends to disap- 

 pear where the glacier becomes crevassed, 

 24, 161 ; renewed from time to tune, 29, 

 39 ; cuts the medial moraines, 39 ; analo- 

 gous appearances in lava, 46, etc. ; results 

 from the limit of perfect plasticity being 

 exceeded, 35, 47, 51, 53, 161, 166, 201; 



forms of veined structure minutely con- 

 sidered, 56, etc. ; subjected to critical ob- 

 servation on the Mer de Glace, 64, etc. ; 

 theory of veined structure illustrated by 

 plastic models, 79 ; perpendicular to 

 crevasses, 79, 81. 



Veined structure, produced in situ, 29, 39, 42, 

 105 ; a consequence of imperfect plasticity, 

 162 ; disappears in glaciers moving torren- 

 tially, 161-2 ; and in the centre of wide 

 glaciers with low velocities, 163 ; remark- 

 able development in 1846 on the glacier 

 of La Brenva, 182 ; its cause explained, 

 182, etc. ; experimentum cruets regarding 

 it, 183, 184 ; analogy from the phenomena 

 of rivers, 185 ; veined structure on Gla- 

 cier of Talefre, 192, 200 ; perpendicular 

 to crevasses there, 192 ; accompanies the 

 conversion of the neve into ice, 53, 200 ; its 

 continuance under medial moraines, 200 ; 

 occurs where pressure is most intense, 

 200. 



Veined structure described generally, 245; 

 course of, 246, 247 ; theorv of, recapitu- 

 lated, 255-8. ^ 



Velocity of glaciers ; maximum not attained 

 simultaneously at all parts of a glacier, 

 or on different glaciers, 135, 139, and 

 note; its dependence on temperature, 138. 



Velocity of glacier at the ice-fall of Talefre, 

 195 ; of Glacier du Nant Blanc, 197. 



Velocity of glaciers, causes which in- 

 fluence it. See Motion and Surface, and 

 the Letters denoting different stations on 

 the Mer de Glace ; also under the names 

 of other glaciers. 



Velocity of lava, 85-93. 



Vesuvius, flow of lava within the crater of, 

 44 ; lavas of Vesuvius, 87. 



Viscous or plastic theory of glacier motion 

 illustrated, 77, etc. ; theory recapitulated, 

 253. See Plastic theory. 



W, station on the Mer de Glace (Glacier of 

 Talefre) so marked, 191, etc., 200. 



Waste, superficial, of glaciers, 33, 60, 241. 

 See Subsidence and Level. 



Water in the crevices of glaciers, its effect, 

 164-166; presumed effect of its congela- 

 tion in winter, 34; this view corrected, 

 60, 156, 158, 218, note, 259. 



Water, ripple in, 58, 80, 185. 



Weather, effects of, on the motion of gla- 

 ciers, 33, 73, 132, 137, 166. 



Weather at Chamouni 1844-5, 133. 



Williamson, Mr., quoted, 110, note. 



Winter, glaciers move in, 25, 36, 129, etc., 

 224, 273 ; glaciers still contain water dur- 

 ing, 137; movement of Glacier of La 

 Brenva in, 179. 



Wrinkles of the surface of the ice discovered, 

 39; probably coincident with the dirt- 

 bands, 40 ; on the Glacier of Grindelwald, 

 41 ; their probable origin, 199 ; their 

 analogues in mud-slides, 213, 214, 216 ; 

 coincident with dirt-bands, 216, 217 ; Mr. 

 MilM-ard's theory of, 261. 



