THE

WONDERS OF GEOLOGY.

LECTURE I.

3. Nature of 5. Extent

18. Geological

1. Introductory remarks. 2. Importance of geology. geology. 4. Harmony between revelation and geology. of geological epochs. 6. Object of the lectures. 7. Physical structure of the earth. 8. Geographical distribution of animals and vegetables. 9. Temperature of the earth. 10. Nature of the crust of the globe. 11. Composition of the rocks and strata. 12. Classification of rocks. 13. Primary rocks. 14. Transition strata. 15. Secondary strata. 16. Tertiary strata. 17. Alluvial deposits. mutations. 19. Connexion of geology with astronomy. 20. Nebular theory of the universe. 21. Different states of nebulæ. 22. Formation of the solar system. 23. Gaseous state of the earth. 24. Geology illustrated by astronomy. 25. Meteorites. 26. Mrs. Somerville on meteorites. 27. Origin of meteorites. 28. Existing geological changes. 29. Effects of streams and rivers. 30. Delta of the Ganges and Mississippi. 31. Formation of strata. 32. Rippled sand. 33. Lewes levels. 34. Remains of man in modern alluvium. 35. Peat bogs. 36. Conversion of peat into coal. 37. Subterranean forests. 38. Geological effects of the sea. 39. Bed of the ocean. 40. Currents and their effects. 41. Incrusting springs. 42. Incrustations not petrifactions. 43. Lake of Solfatara. 44. Marble of Tabreez. Stalactites and stalagmites. 46. Grotto of Antiparos. 47. Consolidation of sand and loose materials. 48. Destruction of rocks by carbonic acid. 49. Carbonic acid gas in caverns and wells. 50. Consolidation of loose strata by iron, 51. Recent formation of marine limestone

B

45.

53.

in the Bermudas. 52. Fossil human skeletons of Guadaloupe. Impressions of human feet in sand-stone. 54. Isle of Ascension. 55. Drifted sand. 56. Sand-flood and recent limestones of Cornwall. 57. Silicious deposits. 58. The Geysers. 59. Hertfordshire conglomerate, or pudding-stone. 60. Effects of high temperature. 61. Volcanic agency. 62. Expansion of rocks by heat. 63. Temple of Jupiter Serapis. 64. Elevation of the coast of Chili. 65. Lifted sea beach at Brighton. 66. Elevation of Scandinavia. 67. Retrospect.

1. INTRODUCTORY REMARKS. It has been observed by a distinguished divine,* that in order to obtain a proper sense of the interest and importance of any science, and of the objects which it embraces, nothing more is necessary than the intent and persevering study of them; and that such is the consummate perfection of all the works of the Creator, that every inquirer will discover a surpassing worth, and grace, and dignity, in that especial department of knowledge to which he may peculiarly devote his attention. Whatever walk of philosophy he may enter, that will appear to him the path which is the most enriched by all that is fitted to captivate the intellect, and to excite the imagination. Yet before we can attain that elevation from which we may look down upon and comprehend the mysteries of the natural world, our way must be steep and toilsome, and we must learn to read the records of creation in a strange language. But when this knowledge is once acquired it becomes a mighty instrument of thought, enables us to link together the phenomena of past and future times, and gives

* Professor Sedgwick.

the mind a domination over many parts of the natural world, by teaching it to comprehend the laws by which the Creator has ordained that the actions of material things shall be governed.

2. IMPORTANCE OF GEOLOGY. -In the whole circle of the sciences, there is perhaps none that more strikingly illustrates the force and truth of these remarks, than Geology; none which offers to its votaries rewards so rich, so wondrous and inexhaustible. In the shapeless pebble that we tread upon, in the rude mass of rock or clay, the uninstructed eye would in vain seek for novelty or beauty; like the adventurer in Eastern fable, the inquirer finds the cavern closed to his entrance, and the rock refusing to give up the treasures entombed within its stony sepulchre, till the talisman is obtained that can dissolve the enchantment, and unfold the marvellous secrets which have so long lain hidden.

3. NATURE Of geology.—To the mind which is unacquainted with the nature and results of geological inquiries, and which has been led to believe that the globe we inhabit is in the state in which it was first created, and that with the exception of the effects of a general deluge, its surface has undergone no material change, many of the facts to be noticed in the course of these lectures may appear almost incredible, and the inferences deduced from their investigation be considered as the vagaries of the imagination rather

than the legitimate inferences of sound philosophy. If, therefore, it be absolutely necessary, as it unquestionably is, that in the pursuit of knowledge of any kind, before even experience can be employed with advantage, we must dismiss from our minds all prejudices, from whatsoever source they may arise, this mental purification becomes the more indispensable in a science like Geology, in which we meet at the very threshold with facts so novel and astounding; teaching us, that although man and other living things be, as it were, but the creation of yesterday, the earth has teemed with numberless forms of animal and vegetable life, myriads of ages ere the existence of the human race.

Geology may be termed the physical history of the earth,—it comprehends the investigation of its structure, and the characters and causes of the various changes which have taken place in the organic and inorganic kingdoms of nature. It has been emphatically called, by one of our most eminent philosophers, the sister science of Astronomy. But, relating as it does to the history of the past, and carrying us back, by the careful examination of the relics of former ages, to periods so remote as to startle all our preconceived opinions of the age of our globe, the fate of its early cultivators has resembled that of the immortal Galileo and the astronomers of his time; and for a similar reason, namely, the supposed discrepancy between the discoveries and inferences of science, and the Mosaic cosmogony,

4. HARMONY BETWEEN REVELATION AND GEOLOGY.-There was a time when every geologist was required to defend himself against imputations of this kind, and I deeply regret to find that there still exists in the minds of many well-meaning persons a prejudice against the study of Geology, from a mistaken apprehension, lest it should weaken our belief in the revealed word of God; for they assume that a discrepancy must exist between the results of geological inquiries and the Mosaic account of the creation of the world. But, convinced as I am of the utter impossibility that there ever can be any collision between the purest piety and sound philosophy, and that these prejudices have been created and perpetuated by authors, who, falsely styling themselves geologists, have mixed up their own vague and erroneous notions with the history of the earth as given by the inspired writer, attempting, with the presumption of ignorance, to account for that which lies beyond the reach of human investigation, and to explain it by evidence equally misapprehended and misapplied, I would most unequivocally assert that a just view of the nature and limits of geological science warrants no such reproach. Abandoning all attempts to explain the inexplicable, or to reconcile the irreconcilable, it confines itself to its legitimate purpose of accumulating and investigating facts, of pointing out analogies, and indicating the inferences to which they lead; "this is far different from that pre