General character of metamorphic rocks — Gneiss — Hornblende-schist — Mica-schist — Clay-slate — Quartzite — Chlorite-schist — Metamorphic limestone — Alphabetical list and explanation of other rocks of this family — Origin of the metamorphic strata — Their stratification is real and distinct from cleavage — Joints and slaty cleavage — Supposed causes of these structures — how far connected with crystalline action [463]

Strata near some intrusive masses of granite converted into rocks identical with different members of the metamorphic series — Arguments hence derived as to the nature of plutonic action — Time may enable this action to pervade denser masses — From what kinds of sedimentary rock each variety of the metamorphic class may be derived — Certain objections to the metamorphic theory considered — Lamination of trachyte and obsidian due to motion — Whether some kinds of gneiss have become schistose by a similar action [473]

Age of each set of metamorphic strata twofold — Test of age by fossils and mineral character not available — Test by superposition ambiguous — Conversion of dense masses of fossiliferous strata into metamorphic rocks — Limestone and shale of Carrara — Metamorphic strata of modern periods in the Alps of Switzerland and Savoy — Why the visible crystalline strata are none of them very modern — Order of succession in metamorphic rocks — Uniformity of mineral character — Why the metamorphic strata are less calcareous than the fossiliferous [481]

Werner's doctrine that mineral veins were fissures filled from above — Veins of segregation — Ordinary metalliferous veins or lodes — Their frequent coincidence with faults — Proofs that they originated in fissures in solid rock — Veins shifting other veins — Polishing of their walls — Shells and pebbles in lodes — Evidence of the successive enlargement and re-opening of veins — Fournet's observations in Auvergne — Dimensions of veins — Why some alternately swell out and contract — Filling of lodes by sublimation from below — Chemical and electrical action — Relative age of the precious metals — Copper and lead veins in Ireland older than Cornish tin — Lead vein in lias, Glamorganshire — Gold in Russia — Connection of hot springs and mineral veins — Concluding remarks [488]

Dates of the successive Editions of the "Principles" and "Elements" (or Manual) of Geology, by the Author.

Principles, 1st vol. in octavo, published in Jan. 1830.
——, 2d vol. do. Jan. 1832.
——, 1st vol. 2d edition in octavo 1832.
——, 2d vol. 2d edition do. Jan. 1833.
——, 3d vol. 1st edition do. May 1833.
——, New edition (called the 3d) of the whole work in 4 vols. 12mo. May 1834.
——, 4th edition, 4 vols. 12mo. June 1835.
——, 5th edition, do. do. Mar. 1837.
Elements, 1st edition in one vol. July 1838.
Principles, 6th edition, 3 vols. 12mo. June 1840.
Elements, 2d edition in 2 vols. 12mo. July 1841.
Principles, 7th edition in one vol. 8vo. Feb. 1847.
——, 8th edition, now published in one vol. 8vo. May 1850.
Manual of Elementary Geology (or "Elements," 3d edition), now published in one vol. 8vo. Jan. 1851.