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because it is told in a familiar manner, it need not be either undignified or unattractive.

Discarding technicalities as much as possible, and avoiding the formality of a text-book, I have still arranged the subjects so as to present a connected view of the science; and he who reads them in order, and understands as he reads, will have a fair conception of the scope and bearings of Geology. At the same time, each sketch is complete in itself, and contains, as far as it goes, an outline of our present knowledge of the matter to which it refers. This mode of treatment may lead to an occasional repetition, but a repetition in such cases is rather an advantage, as tending to render the matter more intelligible, and fix it more enduringly on the memory. I may also mention that several of the topics have been repeatedly brought before miscellaneous audiences in the form of popular lectures, and naturally indulge the hope that what was appreciated by them will prove equally inviting and instructive to the miscellaneous reader.

D. P.

Gilmore Place, Edinburgh,
February 1866.

Second Edition, Published October 1866.
Third Edition, September 1870.

III. VULCANISM—ITS NATURE AND FUNCTION.

DEFINITION OF THE TERM—MODES OF MANIFESTATION—VOL-

CANOES, THEIR VARIOUS ASPECTS, CHARACTERS, PRODUCTS,

AND FUNCTIONS—EARTHQUAKES, THEIR MODES OF ACTION

AND EFFECTS — CONNECTION WITH VOLCANOES — CRUST-

MOTIONS, THEIR CHARACTER AND RESULTS — RECENT EX-

AMPLES — THEORIES OF VULCANISM OR INTERNAL FIRE-

ACTION—ITS SHIFTINGS FROM AREA TO AREA—APPARENT

FUNCTIONS OF—POWER AND PERMANENCE OF, AS A NAT-

URAL FORCE — LAW BY WHICH REGULATED — NECESSARY

PORTION OF WORLD-MECHANISM, . . .51

Iv. Metamorphism, Or The Transformations
Of Rock Matter.

METAMORPHISM, DEFINITION OF THE TERM—ALL ROCK-MATTER

INCESSANTLY UNDERGOING INTERNAL CHANGE THROUGH

PRESSURE, ATTRACTION OF COHESION, CHEMICAL ACTION,

HEAT, MAGNETISM, CRYSTALLISATION, AND OTHER SIMILAR

FORCES—ILLUSTRATIONS OF THESE RESPECTIVE FORCES AND

THEIR MODES OF ACTION—THEIR EFFECTS MOST PERCEPTIBLE

IN THE OLDER ROCKS—THE SO-CALLED METAMORPHIC ROCK-

SYSTEM — APPARENT OBLITERATION OF ITS FOSSILS — GRA-

DUAL DETECTION OF THESE IN PECULIAR LOCALITIES — RE-

SOLUTION OF THE SYSTEM INTO MINOR SECTIONS AND CHRO-

NOLOGICAL ORDER — INCONCEIVABLE AMOUNT OF TIME IM-

PLIED IN THE DEPOSITION AND SUBSEQUENT TRANSFORMA-

TIONS OF THE METAMORPHIC SYSTEM — HOW TO DEAL WITH

IT AS A PART OF WORLD-HISTORY—ITS CONVENIENCE AS A

PROVISIONAL DESIGNATION, . ... 69

V. THE PRIMARY PERIODS.

OLDER AND YOUNGER PORTIONS OF THE EARTH'S CRUST—THESE

REPRESENTED BY PERIODS OF TIME OR SYSTEMS OF STRATA

—TECHNICAL ARRANGEMENT OF THESE TERIODS AND SYS-

TEMS—THE PRIMARY OR EARLIEST YET KNOWN, EMBRACING

THE LAURENTIAN, CAMBRIAN, AND SILURIAN—COMPOSITION

AND DISTRIBUTION OF THESE RESPECTIVE SYSTEMS—THEIR

CHARACTERISTIC ROCKS AND FOSSILS—GENERAL PAUCITY

OF LIFE—ADVANCE DURING THE SILURIAN—CYCLE OF

CRYPTOGAMIC PLANTS AND INVERTEBRATE ANIMALS —

GEOGRAPHICAL ASPECTS OF THE PRIMARY PERIODS—INTER-

EST ATTACHED TO THEM AS THE DAWN OF WORLD-HISTORY, 83

VI. VEINS—THEIR NATURE AND ORIGIN.

VEINS AND DYKES, HOW OCCASIONED — METALLIFEROUS VEIN8,

MOST ABUNDANT IN THE PRIMARY ROCKS—REASON OP THIS

ABUNDANCE—GENERAL CHARACTERISTICS OP VEINS—VARY-

ING NATURE OF THE MINERAL SUBSTANCES BY WHICH VEINS

ARE MAINLY FILLED — MODE IN WHICH THESE VEIN-STUFFS

ARE AGGREGATED—RELATIONS OF THE ORES TO THE VEIN-

STUFFS — DIRECTION OF VEINS IN CERTAIN LOCALITIES—

RIGHT-RUNNING AND CROSS VEINS—THEORIES OF FORMATION

AND FILLING—INFILTRATION AND DEPOSITION OP CHEMICAL

SOLUTIONS—EFFECTS OP THERMAL AGENCY—ELECTRIC AND

OTHER KINDRED CURRENTS — RELATIONS TO CENTRES OF

IGNEOU8 ACTION—IMPORTANCE OF METALLIFEROUS VEINS—

CONTRAST BETWEEN THE MINERAL AND AGRICULTURAL VALUE

OP PRIMARY DISTRICTS—MINES AND STREAM-WORKS—MINING

INDUSTRY, AND IMPORTANCE OF SOUND GEOLOGICAL DEDUC-

TION, . . . . . . .101

VII. FOSSILS—THEIR NATURE AND ARRANGEMENT.

THE TERMS FOSSIL AND SUB-FOSSIL—SCIENCE OF PALAEONTOLOGY

—FOSSILS, HOW IMBEDDED AND PRESERVED—THEIR IM-

PORTANCE IN GEOLOGY — INDICATORS OF GEOGRAPHICAL

CONDITIONS IN THE PAST—OF NATURE AND KIND OF LIFE

DURING SUCCESSIVE PERIODS OF WORLD-HISTORY—DIFFI-

CULTIES ATTENDING PALjEONTOLOGICAL RESEARCH—ORGAN-

ISMS MOST PERFECTLY PRESERVED—PROCESSES OF PETRI-

FACTION—CONDITIONS IN WHICH FOSSILS USUALLY OCCUR

—REQUISITE SKILL FOR THEIR INTERPRETATION—BOTANI-

CAL AND ZOOLOGICAL ARRANGEMENT OF—THIS PRELIMI-

NARY KNOWLEDGE NECESSARY TO THE STUDY OF GENERAL

GEOLOGY, ....... Ill

VIII. THE OLD RED SANDSTONE.

INTEREST ATTACHED TO THE SYSTEM FROM THE LABOURS OF AG-

ASSIZ, HUGH MILLER, AND OTHERS—ITS POSITION IN WORLD-

HISTORY—NATURE OF ITS STRATA—HOW FORMED—LOWER,

MIDDLE, AND UPPER FORMATIONS—TERRAQUEOUS ASFECTS

OF THE PERIOD—ITS FLORA AND FAUNA—GIGANTIC CRUS-

TACEA—VARIED AND ABUNDANT FISH-REMAINS—GEOGRA-

PHICAL OR EXTERNAL CONDITIONS OF THE OLD RED ERA—

ECONOMIC PRODUCTS DERIVED FROM THE SYSTEM—GENE-

RAL REVIEW, ...... 129

IX. COAL AND COAL-FORMATIONS.

COAL, TTS ORIGIN AND FORMATION—MINERALISED VEGETATION

—RECENT PEAT-GROWTHS —TERTIARY LIGNITES—SECOND-

ARY AND PALEOZOIC COALS—PRIMARY ANTHRACITES AND

GRAPHITES—THE COALS AS A MINERAL FAMILY—CONVER-

SION OF VEGETABLE SUBSTANCES INTO COAL—ITS VARIOUS

STAGES—PEAT, LIGNITE, COAL, ANTHRACITE, AND GRAPHITE

—CHARACTERISTICS OF THESE RESPECTIVE STAGES—IMPOR-

TANCE OF COAL TO CIVILISED COUNTRIES—SPECIAL VALUE

OF, TO GREAT BRITAIN, . . . . .143

X. THE OLD COAL-MEASURES.

THE CARBONIFEROUS OR COAL SYSTEM — ITS PLACE IN GEO-

LOGY — NATURE AND COMPOSITION OF ITS STRATA—ITS

UPPER, MIDDLE, AND LOWER DIVISIONS — VARIETIES OF

ITS COALS—APPARENT CAUSES OF—IGNEOUS ROCKS ASSO-

CIATED WITH ITS STRATA—ITS FOSSIL FLORA AND FAUNA

—EXUBERANCE OF ITS PLANT-LIFE—GENERAL GEOGRAPHI-

CAL CONDITIONS OF THE PERIOD—THE COAL-MEASURES AS

AN ECONOMIC REPOSITORY—VARIETY AND VALUE OF ITS

PRODUCTS — THEIR INFLUENCE ON HUMAN CIVILISATION

AND PROGRESS — EXTENT AND DURATION OF PALEOZOIC

COAL-FIELDS, ...... 159

XI. "WHAT WE OWE TO OUR COAL-FIELDS.

Britain's Supremacy In Mechanical And Manufacturing

Industry Dependent On Her Coal-fieldsPhases Of

Modern As Compared With Those Of Ancient Civilisa-

Tions—differences Arising Chiefly From The Use Of

Coal And IronSpecial Products Of Our Coal-fields

Coal And Its VarietiesIron And The Age Of Iron

Limestones And Marbles Sandstones And Their

Relations To ArchitectureFire-clay And Fire-clay

FabricsShales, And The Extraction Of Alum, Cop-

Peras, Paraffin, And Paraffin Oils Ores Of Lead,

Zinc, And Silver Relations Of Mechanical And

Manufacturing Industry To Coal And IronRelations

Of Industry And Commerce To Civilisation And Re-

Finement, . . . . . .177

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