LECTURE VIII. 



Part II. — The Volcanic, and Hypogene or Primary Rocks. 



1. Introductory. 2. Nature of Volcanic action. 3. Earthquakes. 4. Earthquake 

 of Lisbon. 5. Phlegraean Fields, and the Lipari Isles. 6. Ischia and Vesuvius. 

 7. Structure of Volcanic mountains. 8. Volcanic products. 9. Lava currents, 

 Dikes, and Veins. 10. Eruptions of Vesuvius. 11. Herculaneum and Pompeii. 

 12. Conservative effects of Lava streams. 13. Organic remains in Lava. 14. 

 Mount Etna. 15. Val del Bove. 16. Volcano of Kirauea. 17. Mr. Stewart's 

 visit to Kirauea. 18. Volcano of Jorullo. 19. Submarine Volcanoes. 20. Sum- 

 mar}^ of Volcanic phenomena. 21. Hypogene rocks. 22. Mica-schist and Gneiss. 

 23. Contorted Crystalline rocks. 24. Basalt or Trap. 25. Isle of Staffa. 26. Strata 

 altered from contact with Basalt. 27. Trap dikes in the Isle of Sky. 28. Granite. 29. 

 Granitic eruptions. 30. Metamorphism of rocks. 31. Precious stones. 32. Metal- 

 liferous veins. 33. Auriferous alluvia. 34. Cupreous deposits. 35. Transmutation of 

 Metals. 36. Review of the Hypogene rocks. 37. Organic remains in metamor- 

 phic rocks. 38. Chronology of Mountain-chains. 39. Systems of elevation. 40. 

 The Great Caledonian Valley. 41. Structure of Ben Nevis. 42. Retrospect. 43. 

 Successive changes in the Organic Kingdoms. 44. Geological effects of Dynamical 

 and chemical action. 45. Strata composed of Organic Remains. 46. General 

 Inferences. 47. The Ancient World. 48. Corollary. 49. Final Effects. 50. Con- 

 cluding remarks. 



1. Introductory. — We have now passed the boundary 

 which separates the animate from the inanimate world, and 

 have entered those regions of geological research in which 

 all traces of organized beings are absent, and various modifi- 

 cations of mineral substances are the only objects that meet 

 our view. The rocks no longer exhibit those organic 

 characters by which we were enabled to decypher the 

 natural records of the past, entombed in the fossiliferous 

 strata ; but they are inscribed with hieroglyphics whose 

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