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    CHAMBERS'S ELEMENTARY SCIENCE MANUALS.




    GEOLOGY


    BY


    JAMES GEIKIE, LL.D., F.R.S.

    OF H.M. GEOLOGICAL SURVEY; AUTHOR OF
    'THE GREAT ICE AGE.'


    [Logo]

    W. & R. CHAMBERS
    LONDON AND EDINBURGH
    1883




    Edinburgh:
    Printed by W. and R. Chambers.




PREFACE.


The vital importance of diffusing some knowledge of the leading
principles of Science among all classes of society, is becoming daily
more widely and deeply felt; and to meet and promote this important
movement, W. & R. CHAMBERS have resolved on issuing the present Series
of ELEMENTARY SCIENCE MANUALS. The Editors believe that they enjoy
special facilities for the successful execution of such an undertaking,
owing to their long experience--now extending over a period of forty
years--in the work of popular education, as well as to their having the
co-operation of writers specially qualified to treat the several
subjects. In particular, they are happy in having the editorial
assistance of ANDREW FINDLATER, LL.D., to whose labours they were so
much indebted in the work of editing and preparing _Chamber's
Encyclopaedia_.

The Manuals of this series are intended to serve two somewhat different
purposes:

1. They are designed, in the first place, for SELF-INSTRUCTION, and will
present, in a form suitable for private study, the main subjects
entering into an enlightened education; so that young persons in earnest
about self-culture may be able to master them for themselves.

2. The other purpose of the Manuals is, to serve as TEXT-BOOKS IN
SCHOOLS. The mode of treatment naturally adopted in what is to be
studied without a teacher, so far from being a drawback in a
school-manual, will, it is believed, be a positive advantage. Instead of
a number of abrupt statements being presented, to be taken on trust and
learned, as has been the usual method in school-teaching; the subject is
made, as far as possible, to unfold itself gradually, as if the pupil
were discovering the principles himself, the chief function of the book
being, to bring the materials before him, and to guide him by the
shortest road to the discovery. This is now acknowledged to be the only
profitable method of acquiring knowledge, whether as regards
self-instruction or learning at school.

For simplification in teaching, the subject has been divided into
sub-sections or articles, which are numbered continuously; and a series
of Questions, in corresponding divisions, has been appended. These
Questions, while they will enable the private student to test for
himself how far he has mastered the several parts of the subject as he
proceeds, will serve the teacher of a class as specimens of the more
detailed and varied examination to which he should subject his pupils.


NOTE BY THE AUTHOR.

In the present Manual of GEOLOGY it has been the aim of the author
rather to indicate the methods of geological inquiry and reasoning, than
to present the learner with a tedious summary of results. Attention has
therefore been directed chiefly to the physical branches of the
science--Palaeontology and Historical Geology, which are very large
subjects of themselves, having been only lightly touched upon. The
student who has attained to a fair knowledge of the scope and bearing of
Physical Geology, should have little difficulty in subsequently tackling
those manuals in which the results obtained by geological investigation
are specially treated of.




CONTENTS.


                                                                  PAGE
  INTRODUCTORY                                                       7

  CLASSIFICATION OF ROCKS                                            8

  MINERALOGY                                                        12
      ROCK-FORMING MINERALS                                         14

  PETROLOGY--
      MECHANICALLY FORMED ROCKS                                     17
      CHEMICALLY FORMED ROCKS                                       19
      ORGANICALLY DERIVED ROCKS                                     20
      METAMORPHIC ROCKS                                             21
      IGNEOUS ROCKS                                                 23
      STRUCTURE AND ARRANGEMENT OF ROCK-MASSES--
          Stratification, &c.; Mud-cracks and Rain-prints;
          Succession of Strata; Extent of Beds; Sequence of
          Beds--Joints; Cleavage; Foliation; Concretions;
          Inclination of Strata; Contemporaneous Erosion;
          Unconformability; Overlap; Faults; Mode of
          Occurrence of Metamorphic and Igneous Rocks;
          Mineral Veins                                          26-46

  DYNAMICAL GEOLOGY--
      THE ATMOSPHERE AS A GEOLOGICAL AGENT OF CHANGE                46
      WATER AS A GEOLOGICAL AGENT OF CHANGE                         48
      GEOLOGICAL ACTION OF PLANTS AND ANIMALS                       60
      SUBTERRANEAN FORCES                                           64
      METAMORPHISM                                                  72

  PHYSIOGRAPHY                                                      74

  PALAEONTOLOGY                                                      77

  HISTORICAL GEOLOGY                                                