Geology's Greatest Benefactor
October 30, 2014Charles Lyell |
Charles Lyell
(1797–1875). Scientific Papers.
Vol. 38, pp. 385-391 of
The Harvard Classics
Lyell has been
called the founder of modern geology. Darwin, the master scientist,
called him "Geology's Greatest Benefactor." Lyell's
research revolutionized ideas on that subject.
I. The
Progress Of Geology
1 Prepossessions
in regard to the Duration of Past Time—Prejudices Arising from our
Peculiar Position as Inhabitants of the Land—Others Occasioned by
our not seeing Subterranean Changes now in Progress—All these
Causes Combine to make the Former Course of Nature appear Different
from the Present—Objections to the Doctrine that Causes Similar in
Kind and Energy to those now Acting, have Produced the Former Changes
of the Earth’s Surface Considered
IF WE reflect
on the history of the progress of geology *** we perceive that there
have been great fluctuations of opinion respecting the nature of the
causes to which all former changes of the earth’s surface are
referable. The first observers conceived the monuments which the
geologist endeavours to decipher to relate to an original state of
the earth, or to a period when there were causes in activity,
distinct, in a kind and degree, from those now constituting the
economy of nature. These views were gradually modified, and some of
them entirely abandoned, in proportion as observations were
multiplied, and the signs of former mutations were skilfully
interpreted. Many appearances, which had for a long time been
regarded as indicating mysterious and extraordinary agency, were
finally recognised as the necessary result of the laws now governing
the material world; and the discovery of this unlooked-for conformity
has at length induced some philosophers to infer, that, during the
ages contemplated in geology, there has never been any interruption
to the agency of the same uniform laws of change. The same assemblage
of general causes, they conceive, may have been sufficient to
produce, by their various combinations, the endless diversity of
effects, of which the shell of the earth has preserved the memorials;
and, consistently with these principles, the recurrence of analogous
changes is expected by them in time to come.
Whether we coincide or not in this
doctrine we must admit that the gradual progress of opinion
concerning the succession of phenomena in very remote eras,
resembles, in a singular manner, that which has accompanied the
growing intelligence of every people, in regard to the economy of
nature in their own times. In an early state of advancement, when a
greater number of natural appearances are unintelligible, an eclipse,
an earthquake, a flood, or the approach of a comet, with many other
occurrences afterwards found to belong to the regular course of
events, are regarded as prodigies. The same delusion prevails as to
moral phenomena, and many of these are ascribed to the intervention
of demons, ghosts, witches, and other immaterial and supernatural
agents. By degrees, many of the enigmas of the moral and physical
world are explained, and, instead of being due to extrinsic and
irregular causes, they are found to depend on fixed and invariable
laws. The philosopher at last becomes convinced of the undeviating
uniformity of secondary causes; and, guided by his faith in this
principle, he determines the probability of accounts transmitted to
him of former occurrences, and often rejects the fabulous tales of
former times, on the ground of their being irreconcilable with the
experience of more enlightened ages.
Prepossessions in regard to the
duration of past time.—As a belief in the want of conformity in
the cause by which the earth’s crust has been modified in ancient
and modern periods was, for a long time, universally prevalent, and
that, too, amongst men who were convinced that the order of nature
had been uniform for the last several thousand years, every
circumstance which could have influenced their minds and given an
undue bias to their opinions deserves particular attention. Now the
reader may easily satisfy himself, that, however undeviating the
course of nature may have been from the earliest epochs, it was
impossible for the first cultivators of geology to come to such a
conclusion, so long as they were under a delusion as to the age of
the world, and the date of the first creation of animate beings.
However fantastical some theories of the sixteenth century may now
appear to us,—however unworthy of men of great talent and sound
judgment,—we may rest assured that, if the same misconception now
prevailed in regard to the memorials of human transactions, it would
give rise to a similar train of absurdities. Let us imagine, for
example, that Champollion, and the French and Tuscan literati when
engaged in exploring the antiquities of Egypt, had visited that
country with a firm belief that the banks of the Nile were never
peopled by the human race before the beginning of the nineteenth
century, and that their faith in this dogma was as difficult to shake
as the opinion of our ancestors, that the earth was never the abode
of living beings until the creation of the present continents, and of
the species now existing,—it is easy to perceive what extravagant
systems they would frame, while under the influence of this delusion,
to account for the monuments discovered in Egypt. The sight of the
pyramids, obelisks, colossal statues, and ruined temples, would fill
them with such astonishment, that for a time they would be as men
spell-bound—wholly incapable of reasoning with sobriety. They might
incline at first to refer the construction of such stupendous works
to some superhuman powers of the primeval world. A system might be
invented resembling that so gravely advanced by Manetho, who relates
that a dynasty of gods originally ruled in Egypt, of whom Vulcan, the
first monarch, reigned nine thousand years; after whom came Hercules
and other demigods, who were at last succeeded by human kings.
When some fanciful speculations of
this kind had amused their imaginations for a time, some vast
repository of mummies would be discovered, and would immediately
undeceive those antiquaries who enjoyed an opportunity of personally
examining them; but the prejudices of others at a distance, who were
not eye-witnesses of the whole phenomena, would not be so easily
overcome. The concurrent report of many travellers would, indeed,
render it necessary for them to accommodate ancient theories to some
of the new facts, and much wit and ingenuity would be required to
modify and defend their old positions. Each new invention would
violate a greater number of known analogies; for if a theory be
required to embrace some false principle, it becomes more visionary
in proportion as facts are multiplied, as would be the case if
geometers were now required to form an astronomical system on the
assumption of the immobility of the earth.
Amongst other fanciful conjectures
concerning the history of Egypt, we may suppose some of the following
to be started. ‘As the banks of the Nile have been so recently
colonized for the first time, the curious substances called mummies
could never in reality have belonged to men. They may have been
generated by some plastic virtue residing in the
interior of the earth, or they may be abortions of Nature produced by
her incipient efforts in the work of creation. For if deformed beings
are sometimes born even now, when the scheme of the universe is fully
developed, many more may have been “sent before their time scarce
half made up,” when the planet itself was in the embryo state. But
if these notions appear to derogate from the perfection of the Divine
attributes, and if these mummies be in all their parts true
representations of the human form, may we not refer them to the
future rather than the past? May we not be looking into the womb of
Nature, and not her grave? May not these images be like the shades of
the unborn in Virgil’s Elysium—the archetypes of men not yet
called into existence?’
These speculations, if advocated by
eloquent writers, would not fail to attract many zealous votaries,
for they would relieve men from the painful necessity of renouncing
preconceived opinions. Incredible as such scepticism may appear, it
has been rivalled by many systems of the sixteenth and seventeenth
centuries, and among others by that of the learned Falloppio, who, as
we have seen (p. 33), regarded the tusks of fossil elephants as
earthly concretions, and the pottery of fragments of vases in the
Monte Testaceo, near Rome, as works of nature, and not of art. But
when one generation had passed away, and another, not compromised to
the support of antiquated dogmas, had succeeded, they would review
the evidence afforded by mummies more impartially, and would no
longer controvert the preliminary question, that human beings had
lived in Egypt before the nineteenth century: so that when a hundred
years perhaps had been lost, the industry and talents of the
philosopher would be at last directed to the elucidation of points of
real historical importance.
But the above arguments are aimed
against one only of many prejudices with which the earlier geologists
had to contend. Even when they conceded that the earth had been
peopled with animate beings at an earlier period than was at first
supposed, they had no conception that the quantity of time bore so
great a proportion to the historical era as is now generally
conceded. How fatal every error as to the quantity of time must prove
to the introduction of rational views concerning the state of things
in former ages, may be conceived by supposing the annals of the civil
and military transactions of a great nation to be perused under the
impression that they occurred in a period of one hundred instead of
two thousand years. Such a portion of history would immediately
assume the air of a romance; the events would seem devoid of
credibility, and inconsistent with the present course of human
affairs. A crowd of incidents would follow each other in thick
succession. Armies and fleets would appear to be assembled only to be
destroyed, and cities built merely to fall in ruins. There would be
the most violent transitions from foreign or intestine war to periods
of profound peace, and the works effected during the years of
disorder or tranquillity would appear alike superhuman in magnitude.
He who should study the monuments of
the natural world under the influence of a similar infatuation, must
draw a no less exaggerated picture of the energy and violence of
causes, and must experience the same insurmountable difficulty in
reconciling the former and present state of nature. If we could
behold in one view all the volcanic cones thrown up in Iceland,
Italy, Sicily, and other parts of Europe, during the last five
thousand years, and could see the lavas which have flowed during the
same period; the dislocations, subsidences, and elevations caused
during earthquakes; the lands added to various deltas, or devoured by
the sea, together with the effects of devastation by floods, and
imagine that all these events had happened in one year, we must form
most exalted ideas of the activity of the agents, and the suddenness
of the revolutions. If geologists, therefore, have misinterpreted the
signs of a succession of events, so as to conclude that centuries
were implied where the characters indicated thousands of years, and
thousands of years where the language of Nature signified millions,
they could not, if they reasoned logically from such false premises,
come to any other conclusion than that the system of the natural
world had undergone a complete revolution.
We should be warranted in ascribing
the erection of the great pyramid to superhuman power, if we were
convinced that it was raised in one day; and if we imagine, in the
same manner, a continent or mountain-chain to have been elevated
during an equally small fraction of the time which was really
occupied in upheaving it, we might then be justified in inferring,
that the subterranean movements were once far more energetic than in
our own times. We know that during one earthquake the coast of Chili
may be raised for a hundred miles to the average height of about
three feet. A repetition of two thousand shocks, of equal violence,
might produce a mountain-chain one hundred miles long, and six
thousand feet high. Now, should one or two only of these convulsions
happen in a century, it would be consistent with the order of events
experienced by the Chilians from the earliest times: but if the whole
of them were to occur in the next hundred years, the entire district
must be depopulated, scarcely any animals or plants could survive,
and the surface would be one confused heap of ruin and desolation.
One consequence of undervaluing
greatly the quantity of past time, is the apparent coincidence which
it occasions of events necessarily disconnected, or which are so
unusual, that it would be inconsistent with all calculation of
chances to suppose them to happen at one and the same time. When the
unlooked-for association of such rare phenomena is witnessed in the
present course of nature, it scarcely ever fails to excite a
suspicion of the preternatural in those minds which are not firmly
convinced of the uniform agency of secondary causes;—as if the
death of some individual in whose fate they are interested happens to
be accompanied by the appearance of a luminous meteor, or a comet, or
the shock of an earthquake. It would be only necessary to multiply
such coincidences indefinitely, and the mind of every philosopher
would be disturbed. Now it would be difficult to exaggerate the
number of physical events, many of them most rare and unconnected in
their nature, which were imagined by the Woodwardian hypothesis to
have happened in the course of a few months: and numerous other
examples might be found of popular geological theories, which require
us to imagine that a long succession of events happened in a brief
and almost momentary period.
Another liability to error, very
nearly allied to the former, arises from the frequent contact of
geological monuments referring to very distant periods of time. We
often behold, at one glance, the effects of causes which have acted
at times incalculably remote, and yet there may be no striking
circumstances to mark the occurrence of a great chasm in the
chronological series of Nature’s archives. In the vast interval of
time which may really have elapsed between the results of operations
thus compared, the physical condition of the earth may, by slow and
insensible modifications, have become entirely altered; one or more
races of organic beings may have passed away, and yet have left
behind, in the particular region under contemplation, no trace of
their existence.
To a mind unconscious of these
intermediate events, the passage from one state of things to another
must appear so violent, that the idea of revolutions in the system
inevitably suggests itself. The imagination is as much perplexed by
the deception, as it might be if two distant points in space were
suddenly brought into immediate proximity. Let us suppose, for a
moment, that a philosopher should lie down to sleep in some arctic
wilderness, and then be transferred by a power, such as we read of in
tales of enchantment, to a valley in a tropical country, where, on
awaking, he might find himself surrounded by birds of brilliant
plumage, and all the luxuriance of animal and vegetable forms of
which Nature is so prodigal in those regions. The most reasonable
supposition, perhaps, which he could make, if by the necromancer’s
art he were placed in such a situation, would be, that he was
dreaming; and if a geologist form theories under a similar delusion,
we cannot expect him to preserve more consistency in his
speculations, than in the train of ideas in an ordinary dream.
Note
1. The text of the two following papers is taken from the 11th
edition of Lyell’s Principles of Geology, the last edition revised
by the author.
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