Theory of the Earth
by James Hutton
[1788 and 1795]
James Hutton (1726-1797) is considered the father of modern geology.
Although less well known than
Darwin, Hutton's theory
is one of the cornerstones of the modern rationalist view of the world.
Hutton was one of the first scientists to propose that the Earth
is extremely old, much older than the few thousand years that
a literal reading of Genesis would indicate.
This caused a furour much like Darwin's Origin of Species when it was first
Leonardo Da Vinci had privately speculated about this two centuries
earlier in his notebooks,
noting the presence of marine fossils on the top of mountains,
and estimating the huge amount of time it would take
to carve out river valleys.
But Hutton was the first to reject the 'Neptunian' theory of his day
which saw a universal deluge (presumably, the Noachian flood)
as the source of geological formation.
Instead he proposed a 'Vulcanian' theory, in which processes of
heat from the earth's interior had built up continents and mountains
over a long period of time.
In later times this became couched in terms of 'Catastrophism' versus
'Gradualism,' with the gradualists eventually winning out.
This is why conventional geologists reject ideas such as
or pole shifts out of hand, working from first principles.
However, 21st century geologists have become less prickly about
the occasional catastrophic event, such as the Oregon Scablands, which
were formed when a glacial dam broke at the end of the ice ages.
The two texts provided here are his 1788 paper
Theory of the Earth, read before the Royal Society
of Edinburgh, and the two extant volumes of his 1795 book of the same name
in which he not only elaborated his views but defended them against
the bitter criticism that had been leveled against him in the interim.
Although his books, filled with long quotes in French,
make difficult reading, Hutton deserves
to be better known as one of the makers of the modern view of the Earth.
The third volume is available in image format from Google Books.
Theory of the Earth 
Part I. Prospect of the Subject to be treated of.
Part II. An Investigation of the Natural Operations employed in consolidating the Strata of the Globe
Part III. Investigation of the Natural Operations employed in the Production of Land above the Surface of the Sea
Part IV. System of Decay and Renovation observed in the Earth
Theory of the Earth , Volume I
Section I Prospect of the Subject to be treated of
Section II. An Investigation of the Natural Operations employed in consolidating the Strata of the Globe
Section III. Investigation of the Natural Operations employed in the Production of Land above the Surface of the Sea
Section IV. System of Decay and Renovation observed in the Earth
Chapter II. An Examination of Mr KIRWAN'S Objections to the Igneous Origin of Stony Substances
Chapter III. Of Physical Systems, and Geological Theories, in general
Chapter IV. The Supposition of Primitive Mountains refuted
Chapter V. Concerning that which may be termed the Primary Part of the Present Earth
Section I. A distinct View of the Primary and Secondary Strata
Section II. The Theory confirmed from Observations made on purpose to elucidate the subject
Chapter VII. Opinions examined with regard to Petrifaction, or Mineral Concretion
Section I. Purpose of this Inquiry
Section III. The Mineralogical Operations of the Earth illustrated from the Theory of Fossil Coal
Theory of the Earth , Vol. II
Chapter I. Facts in confirmation of the Theory of Elevating Land above the Surface of the Sea
Chapter II. The same Subject continued, with examples from different Countries
Chapter III. Facts in confirmation of the Theory, respecting those Operations which re-dissolve the Surface of the Earth
Chapter IV. The same Subject continued, in giving still farther Views of the Dissolution of the Earth
Chapter V. Facts in confirmation of the Theory respecting the Operations of the Earth employed in forming Soil for Plants
Chapter VI. A View of the Economy of Nature, and necessity of Wasting the Surface of the Earth, in serving the purposes of this World
Chapter VII. The Same Subject continued, in giving a View of the Operations of Air and Water upon the Surface of the Land
Chapter VIII. The present Form of the Surface of the Earth explained, with a View of the Operation of Time upon our Land
Chapter IX. The Theory Illustrated, with a View of the Summits of the Alps
Chapter X. The Theory illustrated with a view of the Valleys of the Alps
Chapter XI. Facts and Opinions concerning the Natural Construction of Mountains and Valleys
Chapter XII. The Theory illustrated, by adducing examples from the different Quarters of the Globe
Chapter XIII. The same Subject continued
Chapter XIV. Summary of the Doctrine which has been now Illustrated