770 



DYNAMICAL GEOLOGY. 



quartz and granite veins and ore were not from igneous fusion ; that water was concerned 

 in metamorphism as well as vein-making; that minerals of various volcanic rocks 

 often contain glass cavities, and also gas or vapor cavities; that some basalts and other 

 igneous rocks have been as much metamorphosed by water as some sedimentary rocks 

 by heat; and gives calculated results as to the pressure under which cavities were made, 

 and thence, less reliable conclusions as to the thickness of the overlying rocks. — The 

 Structure and Origin of Limestones, in his Presidential Address before the Geological 

 Society, in 1879, Quart. J. Geol. Soc, xxxv., 65, 1879. 



A. Delesse: Etudes sur le M&amorphisme des Roches, Annales des Mines, V., xii., 

 89, 417, 795; xiii., 1857: produced as a separate volume, in 1861. 4to, and 1869, 8vo; 

 attributes metamorphism to those agencies which, " as remarked by Elie de Beaumont, 

 are encountered beneath the earth's surface, that is, heat, water, pressure, and molecu- 

 lar action," and plasticity to heat and moisture combined. Sur l'Origine des Roches, 

 etc., Bull. Soc. Geol. de France, II., xv., 728, 1858, and as a separate volume, 1858. 

 Recherches sur les Pseudomorphoses, Annales des Mines, xvi., 1859. 



A. Daubree : fitudes et Experiences Synthe'tiques sur le Metamorphisme, Comptes 

 Rendus, 1860. — Experiences Synthetiques Relatives aux Meteorites, Comptes Rendus, 

 Ixii., 1866. — Eludes Synthe'tiques de Geologie ExpeVimentale, lere Partie, Application 

 de la M^thode Expe>imentale a 1' Eludes de divers Phenomenes Geologiques, 8vo, Paris, 

 1879. These works are made up largely of the results of original research. 



J. Jeffreys : Decomposing action of Steam, Rep. Brit. Assoc, 125, 1840, and Amer. 

 J. Sci., xlviii., 397, 1845. 



R. Tilghman : On the decomposing Power of Water at high Temperatures. Amer. 

 J. Sci., II., v., 266, vi., 260, 1848. 



T. S. Hunt : Origin of Crystalline Rocks, in an Address before the American Asso- 

 ciation in 1871. (See also for criticisms of the views in the address, Amer. J. Sci., III. 

 iii., 86, iv., 41, 97, 1872, and ix., 102, 1875, and Proc Boston Soc. Nat. Hist., xviii., 

 200, Nov , 1875.) On some points in Chemical Geology, Quart. J. Geol. Soc, Nov., 

 1859, and Canadian Naturalist, Dec, 1859. Granites and Granitic veinstones, Amer. 

 J. Sci., III., i., and iii., 1871, 1872. On the Reaction of the Salts of Lime and Magnesia, 

 or on Limestones, Dolomites, and Gypsums, Amer. J. Sci., II., xxviii., 160, 365. See, 

 also, his " Chemical and Geological Essays." 



J. D. Dana: On the Rocks of the Limestone Region of the Green Mountains, includ- 

 ing the Laconic schists in the central and western portion of the region, Amer. J. Sci., 

 III., v., vi., 1873; xiii., xiv., 1877; xvii., 1879. — On the Helderberg Formation of Ber- 

 nardston, Mass., and Vernon, Vt., ibid., xiv., 379. 1877. — On Serpentine Pseudomorphs 

 and other kinds from the Tilly Foster Iron Mine, Putnam Co , N. Y., ibid., viii., 371- 

 1874. Dolomization, Geol. Rep. Wilkes' Expl Exp., 1849, 153, 731, and Amer. J. Sci., 

 vi., 269, 1848. Corals and Coral Islands, p. 357. 



Henry Wurtz: Metamorphism due to heat of friction, Amer. Journal of Mining, 

 Jan. 1868, and Amer. J. Sci., iii., v., 385. 



F. A. Genth : Corundum (of North Carolina), its Alterations and Associated Min- 

 erals, Proc. Amer. Phil. Soc, Philadelphia, 1873. 



5. MINERAL VEINS, LODES, LOCAL OKE-DEPOSITS. 



Veins in rocks have been described, on page 108, as the fillings of 

 cracks or fissures, and they are there divided into (1) dikes, or those 

 that have been filled by an eruption of melted rock, and (2) true 

 veins, those that have been filled by other methods. The distinction 

 is an important one, but is not always easy of application. 



1. Positions. — Fissures, and thereby veins, may be confined to sin- 

 gle beds of rock, or single strata, one bed or stratum being variously 





