702 



DYNAMICAL GEOLOGY. 



may scratch the surface ; but closely-crowded and regular scratches 

 like those of glaciers, over large areas, could hardly be made. The 

 currents of Baffin's Bay flow southward on the west side, and north- 

 ward on the other, — which would give great irregularity there to the 

 scratches of grounded bergs. An iceberg " rocked by the swell of the 

 sea, and sometimes turning over," could not be good at scoring sub- 

 merged rocks. Moreover, these rocks, in the seas in which icebergs 

 melt and drop their freight of stones, would seldom be uncovered. 



The more important works and memoirs on glaciers are the following : — 



Agassiz: Etudes sur les Glaciers, 8vo, Neuchatel, 1840. — Systeme Glaciaire, Nou- 

 velles Etudes et Experiences sur les Glaciers Actuels, 8vo, with an Atlas of 3 maps and 

 9 plates, Paris, 1847. 



J. De Chakpentier: Essai sur les Glaciers et sur le Terrain Erratique du Bassin du 

 Rhone, 8vo, Lausanne, 1841. 



J. D. Fokbes : Travels in the Alps of Savoy, etc., 8vo, Edinburgh, 1843. — Occa- 

 sional Papers on the Theory of Glaciers, 8vo, Edinburgh, 1859. 



J. Tykdall: The Glaciers of the Alps, 8vo, London (and Boston), 1861. — The 

 Forms of Water (in Appletou's International Series), 8vo, New York, 1872. 



Rev. Henry Moseley : Proc. Roy. Soc, xvii., 202, 1869. 



James Ckoll : Climate and Time, 8vo, London, 1875. 

 • James Geikie: The Great Ice Age, London, 1877 (2d ed.). 



Dollfuss-Ausset : Materiaux pour l'fitude des Glaciers, 8 vols., 1864-70. 



The following relate to existing glaciers of the Pacific Coast of North America : — 



Davidson, on the first discovery of glaciers on the Pacific Coast (on Mt. Rainier, 

 Mt. Baker), Proc. Acad. California, iv., 161, 1871, and Am. J. Sci., III. iv., 156, 1872. 

 Clarence King: Glaciers of the Pacific Coast (on Mt. Shasta, Mt. Hood, Mt. Kainier, 

 etc.), Am. J. Sci., III. i., 157, 1871, and Report 40th Parallel, vol. i., 462, 1878. John 

 Muir: Glaciers in California (Sierra Nevada), Overland Monthly, Dec, 1872. Joseph 

 Le Conte : Ancient Glaciers of the Sierra Nevada (with notice of existing), Amer. 

 J. Sci., III. v., 325, x., 126, xviii., 43, 44. Professor LeConte calls the imperfect 

 " Glaciers " noticed b} r Muir and himself in the Sierra Nevada, Glacierets. 



4. WATER AS A CHEMICAL AGENT. 



Water does its chemical work among the rocks, — 

 (1.) Through its capacities as water. 

 (2.) Through the affinities of its elements, directly. 

 (3.) By means of the substances it takes into solution. 

 This work is either destructive or formative. The air aids largely 

 in the results, and hence its chemical effects are here in part included. 



I. DESTRUCTIVE WORK. 



1. Through its Capacities as Water. 



1. At the ordinary Temperature. — It takes 50,000 parts of pure 

 water, at the ordinary temperature, to dissolve one part of calcite or 

 carbonate of lime : over 200,000 for one of a silicate of alumina ; 



