TABLE OF CONTENTS. XV11 



Mechanical disintegration and recomposition of rocks .... 285 



Crystalline silicated rocks of stratified formations -. 286 



Two hypotheses to explain their origin 286 



Alleged pseudomorphous change of plutonic rocks 286 



The doctrine of pseudomorphism by alteration 287 



Symmetrical and asymmetrical envelopment of minerals .... 288 



Difficulties of the doctrine of pseudomorphous alteration . . . 290 



Scheerer's doctrine of polymeric isomorphism 291 



Delesse and Naumann on pseudomorphism ...... 292 



Supposed plutonic origin of crystalline stratified rocks .... 294 



Views of Naumann and of Macfarlane on primary rocks . . . 294 



Hypothesis of the aqueous origin of crystalline rocks .... 296 



Generation of silicates in cases of local alteration 297 



Aqueous deposition of feldspathic minerals 298 



Alleged palaeozoic age of many crystalline schists .... 299 



The author's view of their origin defined 300 



Early views of the aqueous origin of crystalline rocks .... 301 



Evidences of life at the time of their deposition 301 



Evidences of life afforded by meteoric stones ...... 302 



Discovery of the Eozoon Canadense 302 



Silicates injecting this and various other organisms .... 303 



Observations of Giimbel, Hoffmann, and Dawson ..... 303 



Credner and Giimbel on the origin of crystalline schists . . . 304 



Giimbel on diagenesis and epigenesis 305 



Note containing the views of Giimbel on this question .... 305 



Note on the crystalline aggregation of finely divided matter . . . 305 



Conditions of early times favoring diagenesis 306 



The origin and formation of dolomites 307 



Influence of carbonic acid on the production of dolomite . . . 308 



Supposed generation of dolomite by Von Morlot and Marignac . . 308 



Two classes of dolomites ; their origin 310 



Relations of one class of these to gypsum and rock-salt .... 310 



Former climate of eastern North America . 310 



Magnesian silicates of Syracuse, New York 310 



Supposed organic origin of limestones 311 



Their true relation to organic life 311 



Relations of phosphates to organisms 311 



Phosphatic nature of Lingula, Orbicula, Conularia, etc 312 



Relations of silica to organic life ........ 312 



APPENDIX. 



Reply to Mr. Dana's criticisms 313 



The question of the transmutation of species stated .... 313 



Warrington Smyth's opinion of epigenesis ...... 313 



The views of Delesse on pseudomorphism defined .... 314 



Delesse on the eruptive origin of serpentine 316 



He subsequently adopts the view of its aqueous origin . . . . 317 



A revolution in the theory of crystalline rocks 317 



Scheerer's views explained and defended 318 



