ORIGIN OF CRYSTALLINE ROCKS. 67 



and basaltic magmas and of palagonite (foot-note).— 67, 68. A primary quartzless roclc tlie source of 

 granite and of crystalline schists.— 69. Its separation by water into a lower basic, and an upper acidic 

 portion.— 70. Shrinking of the former and wrinkling of the latter ; exoplutonic rocks ; the crenitic hypo- 

 thesis.— 71. Its growth from 1858 to 1884. 



lU.—Illuslralions of the Crenitic Hypothem.—^ 72- Tlie new hypothesis defined.— 73, 74. The study of zeolitic rocks. , 

 —75. Zeolites of Table Mountain, Colorado.— 76. Zeolites and feldspathic veins of Mount Royal.— 77. The 

 mineral secretions of basic rocks classified.— 78. Zeolites and related silicates ; a tabular view.— 79. The 

 thomsonite and nephelite series.— SO. Barsowite, iohte, and related species ; the natrolite and labrado- 

 rite series; the faujasite and heulandite series; orlhoclase.— 81. Prehnite and chlorastrohte ; epidote, 

 saussurite and meionite.— 82. The protoxyd bases of zeolites ; hematite and magnetite ; tlie pectohtic 

 group and its related species; chondrodite, chrysolite, serpentine, deweylite; tabular view.— 84. The 

 bisilicates, hydrous and anhydrous.— 85. Quadrisilicates.— 86, 87- Daubrée on the action of hot water 

 on glass ; formation of quartz, diopside, a pectolitic species, and a soluble silicate of alumina and soda. 

 -88. His farther stu<lies of feldspars, etc. ; Frémy on alkaline silicates.— 89. Ordway on alkaline sihcates ; 

 solutions of water-glass dissolve metallic oxyds.— 90, 91. The thermal waters of Plombières ; recent 

 formation of zeolitic and pectolitic silicates, quartz and calcite.— 92. The alteration of bricks by these 

 warm waters.— 93. Similar studies at other thermal springs.— 94. Recent production of zeolites in basalt 

 and sandstone.— 95. Their formation in deei>sea ooze.- 96, 97. The production of zeolitic silicates in the 

 laboratory ; results of Berzelius, Ammon, and Way.— 98. H. Deville on the formation of zeolites and 

 quartz.— 99. Friedel and Sarrasin on the production of both zeolites and feldspars in heated solutions. 

 —100. Aluminous silicates with excess o^ protoxyd bases ; their genesis. — 101. Reactions of zeolites with 

 magnesian solutions; Way, Eichhorn, Bunsen.— 102. Aluminous silicates with deficiency of protoxyds, 

 and simple aluminous silicates; muscovitic micas. — 103. Probable origin of these silicates. — 104. Pinite 

 and related species ; their composition. — 105. Their importance in nature ; the survival of the fittest. — 

 106. The supposed chemical relations of pinite— 107, 108. A natural system of mineralogical classi- 

 fication.— 109. Conditions of crystallization from water; solubihty of silicates and oxyds.— 110. Tempo- 

 rary solubility of carbonate of lime; a hydrocarbonate.— 111. Conversion of amorphous into crystaUine 

 matters ; cerium-oxalates ; malate of lead.— 112. Crystallization of hydrous magnesian carbonate, and 

 hydrous double carbonates of lime and magnesia ; gaylussite ; the soda-dolomite of H. Deville. — 113. 

 Dolomite, its geognostical and chemical history ; its origin and formation explained. — 114. The process 

 of diagenesis. — 115. Conversion of smaller into larger crystals ; chemical union. — 116. Crystallization of 

 dissolved matters around nuclei ; examples from quartz and orthoclase. 



\y .— Conclusions. — §117. The crenitic hypothesis re-stated. — 118 Separation of magnesian salts from sea-water ; 

 the relations of carbonates and silicates of lime and magnesia. — 119. Elimination of magnesia from the 

 primeval sea ; decomposition of i^ectolitic silicates by carbonic acid, and formation of limestone. — 120. 

 First exoplutonic action ; results of contraction of the primary mass. — 121. Sub-aerial decay of exotic 

 rocks a source of magnesian salts ; their reaction with pectolitic silicates. — 122. Decomposition of alka- 

 line silicates ; formation of quartz and basic silicates; oxyds of the spinel and corundum groups ; their 

 formation. — 123. Surbasic aluminous silicates ; rocks of the Huronian time. — 124. Absence of magnesia 

 from sea-basins ; Montalban gneisses and ,mica-schists ; sub-aerial decay ; boulders of decomposition ; 

 iolite-gneiss.— 125. Taconian series; its micaceous schists; Laurentian, Arvonian, Norian, Huronian, 

 Montalban and Taconian series ; their relations noted. — 126. Later evidences of crenitic action; Silurian 

 serpentine and tertiary sepiolite ; conditions of deposition of aluminous silicates compatible with life. — 

 127. Exoplutonic or volcanic phenomena ; their probable three-fold origin. — 128. The history of crystal- 

 line rocks resumed. — 129. Their changes in time and place ; grounds of an aqueous hypothesis and an 

 igneous point of departure ; fire as a destroyer, water as an organizer ; relations of palagonite ; separa- 

 tion of the primary mass into basic and acidic layers. — 130. Marks of a valid hypothesis; claims of the 

 one here proposed. 



Note. — The observations of Vauliise, cited in § 116, have appeared since the presenta- 

 tion of this paper in May, 1884. The same is true of those of Murray and Renard, referred 

 to in § 95, though these had previovisly been communicated to the present writer. 



