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Principles of
Geology
by Sir Charles Lyell
CHAPTER III.
Arabian writers of the Tenth
century-Persecution of Omar - Cosmogony of the Koran - Early Itatian writers -
Fracastoro - controversy as to the real nature of organized fossils - Fossil
shells attributed to the Mosaic deluge - Palissy - Steno - Scilla - Quirini -
Boyle - Plot - Hooke's Theory of Elevation by earthquakes - His speculations on
lost species of animals - Ray - Physico - theological writers-Woodward's
Diluvial Theory - Burnet - Whiston - Hutchinson - Leibnitz - Vallisneri -
Lazzoro Moro - Generelii - Buffon - His theory condemned by the Sorbonne as
unorthodox - Buffon's declaration - Targioni - Arduino - Michell - Catcott -
Raspe - Fortis - Testa - Whitehurst - Palias - Saussure.
AFTER the decline of the Roman
empire, the cultivation of physical science was first revived with some success
by the Saracens, about the middle of the eighth century of our era. The works of
the most eminent classic writers were purchased at great expense from the
Christians, and translated into Arabic; and Al Mamun, son of the famous Harunal
Rashid, the contemporary of Charlemagne, received with marks of distinction, at
his court at Bagdad, astronomers and men of learning from different countries.
This caliph, and some of his successors, encountered much opposition and
jealousy from the doctors of the Mahomedan law, who wished the Moslems to
confine their studies to the Koran, dreading the effects of the diffusion of a
taste for the physical sciences. Almost all the works of the early Arabian
writers are lost. Amongst those of the tenth century, of which fragments are now
extant, is a system of mineralogy by Avicenna a physician, in whose arrangement
there is considerable merit. In the same century also, Omar, surnamed "El Aalem,"
or " the Learned," wrote a work on "the Retreat of the Sea." It appears that on
comparing the charts of his own time with those made by the Indian and Persian
astronomers two thousand years before, he had satisfied himself that important
changes had taken place since the times of history in the form of the coasts of
Asia, and that the extension of the sea had been greater at some former periods.
He was confirmed in this opinion by the numerous salt springs and marshes in the
interior of Asia; a phenomenon from which Pallas, in more recent times, has
drawn the same inference.
Von Hoff has suggested, with
great probability, that the changes in the level of the Caspian, (some of which
there is reason to believe have happened within the historical era, and the
geological appearances in that district, indicating the desertion by that sea of
its ancient bed, had probably led Omar to his theory of a general subsidence.
But whatever may have been the proofs relied on, his system was declared
contradictory to certain passages in the Koran, and he was called upon publicly
to recant his errors; to avoid which persecution he went into voluntary
banishment from Samarkand.
The cosmological opinions
expressed in the Koran are few, and merely introduced incidentally; so that it
is not easy to understand how they could have interfered so seriously with free
discussion on the former changes of the globe. The Prophet declared that the
earth was created in two days, and the mountains were then placed on it; and
during these, and two additional days, the inhabitants of the earth were formed;
and in two more the seven heavens. There is no more detail of circumstances, and
the deluge, which is also mentioned, is discussed with equal brevity. The waters
are represented to have poured out of an oven; a strange fable, said to be
borrowed from the Persian Magi, who represented them as issuing from the oven of
an old woman. All men were drowned, save Noah and his family; and then God said,
"O earth, swallow up thy waters; and thou, O heaven, withhold thy rain;" and
immediately the waters abated.
We may suppose Omar to have
represented the desertion pothesis required a greater lapse of ages than was
consistent with Moslem orthodoxy; for it is to be inferred from the Koran, that
man and this planet were created at the same time; and although Mahomet did not
limit expressly the antiquity of the human race, yet he gave an implied sanction
to the Mosaic chronology by the veneration expressed by him for the Hebrew
Patriarchs.
We must now pass over an
interval of five centuries, wherein darkness enveloped almost every department
of science, and buried in profound oblivion all prior investigations into the
earth's history and structure. It was not till the earlier part of the sixteenth
century that geological phenomena began to attract the attention of the
Christian nations. At that period a very animated controversy sprung up in
Italy, concerning the true nature and origin of marine shells, and other
organized fossils, found abundantly in the strata of the peninsula. The
excavations made in 1517, for repairing the city of Verona, brought to light a
multitude of curious petrifactions, and furnished matter for speculation to
different authors, and among the rest to Fracastoro, who declared his opinion,
that fossil shells had all belonged to living animals, which had formerly lived
and multiplied, where their exuviae are now found. He exposed the absurdity of
having recourse to a certain "plastic force," which it was said had power to
fashion stones into organic forms; and, with no less cogent arguments,
demonstrated the futility of attributing the situation of the shells in question
to the Mosaic deluge, a theory obstinately defended by some. That inundation, he
observed, was too transient, it consisted principally of fluviatile waters; and,
if it had transported shells to great distances, must have strewed them over the
surface, not buried them at vast depths in the interior of mountains. His clear
exposition of the evidence would have terminated the discussion for ever if the
passions of mankind had not been enlisted in the dispute; and even though doubts
should for a time have remained in some minds, they would speedily have been
removed by the fresh information obtained almost immediately afterwards,
respecting the structure of fossil remains, and of their living analogues. But
the clear and philosophical views of Fracastoro were disregarded, and the talent
and argumentative powers of the learned were doomed for three centuries to be
wasted in the discussion of these two simple and preliminary questions: first,
whether fossil remains had ever belonged to living creatures; and, secondly,
whether, if this be admitted, all the phenomena could be explained by the
Noachian deluge. It had been the consistent belief of the Christian world, down
to the period now under consideration, that the origin of this planet was not
more remote than a few thousand years; and that since the creation the deluge
was the only great catastrophe by which considerable change had been wrought on
the earth's surface. On the other hand, the opinion was scarcely less general,
that the final dissolution of our system was an event to be looked for at no
distant period. The era, it is true, of the expected millennium had passed away;
and for five hundred years after the fatal hour, when the annihilation of the
planet had been looked for, the monks remained in undisturbed enjoyment of rich
grants of land bequeathed to them by pious donors, who, in the preamble of deeds
beginning "appropinquante mundi terrnino"-"appropinquante magno judicii die,"
left lasting monuments of the popular delusion.
But although in the sixteenth
century it had become necessary to interpret the prophecies more liberally, and
to assign a more distant date to the future conflagration of the world, we find,
in the speculations of the early geologists, perpetual allusion to such an
approaching, catastrophe; while, in all that regarded the antiquity of the
earth, no modification whatever of the opinions of the dark ages had been
erected. Considerable alarm was at first excited when the attempt was made to
invalidate by physical proofs an article of faith so generally received, but
there was sufficient spirit of toleration and candour amongst the Italian
ecclesiastics, to allow the subject to be canvassed with much freedom. They
entered warmly themselves into the controversy, often favouring different sides
of the question; and however much we may deplore the loss of time and labour
devoted to the defence of untenable positions, it must be conceded, that they
displayed far less polemic bitterness than certain writers who followed them
"beyond the Alps" two centuries and a half later.
The system of scholastic
disputations encouraged in the Universities of the middle ages had unfortunately
trained men to habits of indefinite argumentation, and they often preferred
absurd and extravagant propositions, because greater still was required to
maintain them; the end and object of such intellectual combats being victory and
not truth. No theory could be too farfetched or fantastical not to attract some
followers, provided it fell in with popular notions; and as cosmologists were
not at all restricted, in building their systems, to the agency of known causes,
the opponents of Fracastoro met his arguments by feigning imaginary causes,
which differed from each other rather in name than in substance. Andrea
Mattioli, for instance, an eminent botanist, the illustrator of Dioscorides,
embraced the notion of Agricola, a German miner, that a certain "materia
pinguis" or "fatty matter," set into fermentation by heat, gave birth to fossil
organic shapes. Yet Mattioli had come to the conclusion from his own
observations, that porous bodies, such as bones and shells, might be converted
into stone, as being permeable to what he termed the "lapidifying juice." In
like manner, Falloppio of Padua conceived that petrified shells bad been
generated by fermentation in the spots where they were found, or that they had
in some cases acquired their form from "the tumultuous movements of terrestrial
exhalations" Although not an unskillful professor of anatomy, he taught that
certain tusks of elephants dug up in his time at Puglia were mere earthy
concretions, and, consistently with these principles, he even went so far as to
consider it not improbable, that the vases of Monte Testaceo at Rome were
natural impressions stamped in the soil. In the same spirit, Mercati, who
published, in 1574, faithful figures of the fossil shells preserved by Pope
Sextus V in the Museum of the Vatican, expressed an opinion that they were mere
stones, which had assumed their peculiar configuration from the influence of the
heavenly bodies; and Olivi of Cremona, who described the fossil remains of a
rich Museum at Verona, was satisfied with considering them mere "sports of
nature."
The title of a work of
Cardano's, published in 1552, "De Subtilitate," (corresponding to what would now
be called, Transcendental Philosophy,) would lead us to expect in the chapter on
minerals, many farfetched theories characteristic of that age; but, when
treating of petrified shells, he decided that they clearly indicated the former
sojourn of the sea upon the mountains.
Some of the fanciful notions of
those times were deemed less unreasonable, as being somewhat in harmony with the
Aristotelian theory of spontaneous generation, then taught in all the schools.
For men who had been instructed in early youth, that a large proportion of
living animals and plants were formed from the fortuitous concourse of atoms, or
had sprung from the corruption of organic matter, might easily persuade
themselves, that organic shapes, often imperfectly preserved in the interior of
solid rocks, owed their existence to causes equally obscure and mysterious.
But there were not wanting
some, who at the close of this century expressed more sound and sober opinions.
Cesalpino, a celebrated botanist, conceived that fossil shells had been left on
the land by the retiring sea, and had concreted into stone during the
consolidation of the soil; and in the following year (1597), Simeone Majoli went
still further, and, coinciding for the most part with the views of Cesalpino,
suggested that the shells and submarine matter of the Veronese, and other
districts, might have been cast up, upon the land, by volcanic explosions, like
those which gave rise, in 1588, to Monte Nuovo, near Puzzuoli.-This hint was the
first imperfect attempt to connect the position of fossil shells with the agency
of volcanoes, a system afterwards more fully developed by Hooke, Lazzoro Moro,
Hutton, and other writers.
Two years afterwards, Imperati
advocated the animal origin of fossilized shells, yet admitted that stones could
vegetate by force of "an internal principle;" and, as evidence of this, he
referred to the teeth of fish, and spines of echini found petrified.
Palissy, a French writer on
"the Origin of Springs from Rainwater" and of other scientific works, undertook,
in 1580, to combat the notions of many of his contemporaries in Italy, that
petrified shells had all been deposited by the universal deluge. "He was the
first," said Fontenelle, when, in the French Academy, he pronounced his eulogy
more than fifty years afterwards, " who dared assert" in Paris, that fossil
remains of testacea and fish had once belonged to marine animals.
To enumerate the multitude of
Italian writers, who advanced various hypotheses, all equally fantastical, in
the early part of the seventeenth century, would be unprofitably tedious, but
Fabio Colonna deserves to be distinguished; for, although he gave way to the
dogma, that all fossil remains were to be referred to the Noachian deluge, he
resisted the absurd theory of Stelluti, who taught that fossil wood and
ammonites were mere clay, altered into such forms by sulphureous waters and
subterranean heat; and he pointed out the different states of shells buried in
the strata, distinguishing between, first, the mere mould or impression;
secondly, the cast or nucleus; and thirdly, the remains of the shell itself. He
had also the merit of being the first to point out, that some of the fossils had
belonged to marine, and some to terrestrial testacea. But the most remarkable
work of that period was published by Steno, a Dane, once professor of anatomy at
Padua, and who afterwards resided many years at the court of the Grand Duke of
Tuscany. The treatise bears the quaint title of " De Solido intra Solidum
contento naturaliter, (1669,)" by which the author intended to express "On Gems,
Crystals, and organic Petrifactions inclosed within solid Rocks." This work
attests the priority of the Italian school in geological research; exemplifying
at the same time the powerful obstacles opposed, in that age, to the general
reception of enlarged views in the science. Steno had compared the fossil shells
with their recent analogues, and traced the various gradations from the state of
mere calcination, when their natural gluten only was lost, to the perfect
substitution of stony matter. He demonstrated that many fossil teeth found in
Tuscany belonged to a species of shark; and he dissected, for the purpose of
comparison, one of these fish recently taken from the Mediterranean. That the
remains of shells and marine animals found petrified were not of animal origin
was still a favourite dogma of many who were unwilling to believe, that the
earth could have been inhabited by living beings, long before many of the
mountains were formed. By way of compromise, as it were, for dissenting from
this opinion, Steno conceded, as Fabio Colonna had done before him, that all
marine fossils might have been transported into their present situation at the
time of the Noachian deluge. He maintained that fossil vegetables had been once
living plants, and he hinted that they might, in some instances, indicate the
distinction between fluviatile and marine deposits. He also inferred that the
present mountains had not existed ever since the origin of things, suggesting
that many strata of submarine origin had been accumulated in the interval
between the creation and deluge. Here he displayed his great anxiety to
reconcile his theory with the Scriptures; for he at the same time advanced an
opinion, which does not seem very consistent with such a doctrine, viz. that
there was a wide distinction between the shelly, and nearly horizontal beds at
the foot of the Apen nines, and the older mountains of highly inclined
stratification. Both, he observed, were of sedimentary origin; and a
considerable interval of time must have separated their formation. Tuscany,
according to him, had successively past through six different states; and
to explain these mighty changes, he called in the agency of inundations,
earthquakes, and subterranean fires.
His generalizations were for
the most part comprehensive and just; but such was his awe of popular prejudice,
that he only ventured to throw them out as mere conjectures, and the timid
reserve of his expressions must have raised doubts as to his own confidence in
his opinions, and deprived them of some of the authority due to them.
Scilla, a Sicilian painter,
published, in 1670, a work on the fossils of Calabria, illustrated by good
engravings. This was written in Latin, with great spirit and elegance, and it
proves the continued ascendancy of dogmas often refuted; for we find the wit and
eloquence of the author chiefly directed against the obstinate incredulity of
naturalists, as to the organic nature of fossil shells. Like many eminent
naturalists of his day, Scilla gave way to the popular persuasion that all
fossil shells were the effects and proofs of the Mosaic deluge. It may be
doubted whether he was perfectly sincere, and some of his contemporaries who
took the same course were certainly not so. But so eager were they to root out
what they justly considered an absurd prejudice respecting the nature of
organized fossils, that they seem to have been ready to make any concessions, in
order to establish this preliminary point. Such a compromising policy was
shortsighted, since it was to little purpose that the nature of the documents
should at length be correctly understood, if men were to be prevented from
deducing fair conclusions from them.
The theologians who now entered
the field in Italy, Germany, France and England, were innumerable; and
henceforward, they who refused to subscribe to the position, that all marine
organic remains were proofs of the Mosaic deluge, were exposed to the imputation
of disbelieving the whole of the sacred writings. Scarcely any step had been
made in approximating to sound theories since the time of Fracastoro, more than
a hundred years having been lost, in writing down the dogma that organized
fossils were mere sports of nature. An additional period of a century and a half
was now destined to be consumed in exploding the hypothesis, that organized
fossils had all been buried in the solid strata, by the Noachian flood. Never
did a theoretical fallacy, in any branch of science, interfere more seriously
with accurate observation and the systematic classification of facts. In recent
times, we may attribute our rapid progress chiefly to the careful determination
of the order of succession in mineral masses, by means of their different
organic contents, and their regular superposition. But the old diluvialists were
induced by their system to confound all the groups of strata together instead of
discriminating,-to refer all appearances to one cause and to one brief period,
not to a variety of causes acting throughout a long succession of epochs. They
saw the phenomena only as they desired to see them, sometimes misrepresenting
facts, and at other times deducing false conclusions from correct data. Under
the influence of such prejudices, three centuries were of as little avail, as
the same number of years in our own times, when we are no longer required to
propel the vessel against the force of an adverse current.
It may be well to forewarn our
readers, that in tracing the history of geology from the close of the
seventeenth to the end of the eighteenth century, they must expect to be
occupied with accounts of the retardation, as well as of the advance of the
science. It will be our irksome task to point out the frequent revival of
exploded errors, and the relapse from sound to the most absurd opinions. It will
be necessary to dwell on futile reasoning and visionary hypothesis, because the
most extravagant systems were often invented or controverted by men of
acknowledged talent. A sketch of the progress of Geology is the history of a
constant and violent struggle between new opinions and ancient doctrines,
sanctioned by the implicit faith of many generations, and supposed to rest on
scriptural authority. The inquiry, therefore, although highly interesting to one
who studies the philosophy of the human mind, is singularly barren of
instruction to him who searches for truths in physical science.
Quirini, in 1676, contended, in
opposition to Scilla, that the diluvian waters could not have conveyed heavy
bodies to the summit of mountains, since the agitation of the sea never (as
Boyle had demonstrated) extended to great depths, and still less could the
testacea, as some pretended, have lived in these diluvial waters, for "the
duration of the flood was brief, and the heavy rains must have destroyed the
saltness of the sea!" He was the first writer who ventured to maintain that
the universality of the Noachian cataclysm ought not to be insisted upon. As to
the nature of petrified shells, he conceived that as earthy particles united in
the sea to form the shells of mollusca, the same crystallizing process might be
expected on the land, and that, in the latter case, the germs of the animals
might have been disseminated through the substance of the rocks, and afterwards
developed by virtue of humidity. Visionary as was this doctrine, it gained many
proselytes even amongst the more sober reasoners of Italy and Germany, for it
conceded both that fossil bodies were organic, and that the diluvial theory
could not account for them.
In the mean time, the doctrine
that fossil shells had never belonged to real animals, maintained its ground in
England, where the agitation of the question began at a much later period. Dr.
Plot, in his "Natural History of Oxfordshire," (1677,) attributed to "a plastic
virtue latent in the earth" the origin of fossil shells and fishes; and Lister,
to his accurate account of British shells, in 1678, added the fossil species,
under the appellation of turbinated and bivalve stones. "Either," said
he, "these were terriginous, or, if otherwise, the animals they so exactly
represent have become extinct." This writer appears to have been the
first who was aware of the continuity over large districts of the principal
groups of strata in the British series, and who proposed the construction of
regular geological maps.
The "Posthumous Works of Robert
Hooke, M.D.," well known as a great mathematician and natural philosopher,
appeared in 1705, containing, "A Discourse of Earthquakes," which, we are
informed by his editor, was written in 1668, but revised at subsequent periods.
Hooke frequently refers to the best Italian and English authors who wrote before
his time on geological subjects; but there are no passages in his works implying
that he participated in the enlarged views of Steno and Lister, or of his
contemporary Woodward, in regard to the geographical extent of certain groups of
strata. His treatise, however, is the most philosophical production of that age,
in regard to the causes of former changes in the organic and inorganic kingdoms
of nature.
"However trivial a thing," he
says, " a rotten shell may appear to some, yet these monuments of nature are
more certain tokens of antiquity than coins or medals, since the best of those
may be counterfeited or made by art and design, as may also books, manuscripts,
and inscriptions, as all the learned are now sufficiently satisfied has often
been actually practiced," &c.; "and though it must be granted that it is very
difficult to read them (the records of nature) and to raise a chronology out
of them, and to state the intervals of the time wherein such or such
catastrophes and mutations have happened, yet it is not impossible," &c.
Respecting the extinction of species, Hooke was aware that the fossil ammonites,
nautili, and many other shells and fossil skeletons found in England, were of
different species from any then known; but he doubted whether the species had
become extinct, observing that the knowledge of naturalists of all the marine
species, especially those inhabiting the deep sea, was very deficient. In some
parts of his writings, however, he leans to the opinion that species had been
lost; and, in speculating on this subject, he even suggests that there might be
some connection between the disappearance of certain kinds of animals and
plants, and the changes wrought by earthquakes in former ages: for some species,
he observes with great sagacity, are "peculiar to certain places, and not
to be found elsewhere. If, then, such a place had been swallowed up, it is not
improbable but that those animate beings may have been destroyed with it; and
this may be true both of aerial and aquatic animals: for those animated bodies,
whether vegetables or animals, which were naturally nourished or refreshed by
the air, would be destroyed by the water," &c. Turtles, he adds, and such large
ammonites as are found in Portland, seem to have been the productions of the
seas of hotter countries, and it is necessary to suppose that England once
lay under the .sea within the torrid zone! To explain this and similar
phenomena, he indulges in a variety of speculations concerning changes in
the position of the axis of the earth's rotation, a shifting of the
earth's centre of gravity, "analogous to the revolutions of the
magnetic pole," &c. None of these conjectures, however, are proposed
dogmatically, but rather in the hope of promoting fresh inquiries and
experiments.
In opposition to the prejudices
of his age, we find him arguing that nature had not formed fossil bodies, "for
no other end than to play the mimic in the mineral kingdom"-that figured stones
were "really the several bodies they represent, or the mouldings of them
petrified," and "not, as some have imagined, a 'lusus naturae,' sporting herself
in the needless formation of useless beings."
It was objected to Hooke, that
his doctrine of the extinction of species derogated from the wisdom and power of
the omnipotent Creator; but he answered, that, as individuals die, there may be
some termination to the duration of a species; and his opinions, he declared,
were not repugnant to Holy Writ: for the Scriptures taught that our system was
degenerating, and tending to its final dissolution; "and as, when that shall
happen, all the species will be lost, why not some at one time and some at
another?
But his principal object was to
account for the manner in which shells had been conveyed into the higher parts
of "the Alps, Apennines, and Pyrenean hills, and the interior of continents in
general." These and other appearances, he said, might have been brought about by
earthquakes, which have turned plains into mountains, and mountains into plains,
seas into land, and land into seas, made rivers where there were none before,
and swallowed up others that formerly were, &c. &c.; and which, since the
creation of the world, have wrought many great changes on the superficial parts
of thc earth, and have been the instruments of placing shells, bones, plants,
fishes, and the like, in those places, where, with much astonishment, we find
them." This doctrine, it is true, had been laid down in terms almost equally
explicit by Strabo, to explain the occurrence of fossil shells in the interior
of continents, and to that geographer, and other writers of antiquity, Hooke
frequently refers; but the revival and developement of the system was an
important step in the progress of modern science.
He enumerated all the examples
known to him of subterranean disturbance, from "the sad catastrophe of Sodom and
Gomorrah" down to the Chilian earthquake of 1646. The elevating of the bottom of
the sea, the sinking and submersion of the land, and most of the inequalities of
the earth's surface, might, he said, be accounted for by the agency of these
subterranean causes. He mentions that the coast near Naples was raised during
the eruption of Monte Nuovo; and that, in 1591, land rose in the island of St.
Michael, during an eruption; and although it would be more difficult, he says,
to prove, he does not doubt but that there had been as many earthquakes in
the parts of the earth under the ocean, as in the parts of the dry land; in
confirmation of which he mentions the immeasurable depth of the sea near some
volcanoes. To attest the extent of simultaneous subterranean movements, he
refers to an earthquake in the West Indies, in 1690, where the space of earth
raised, or "struck upwards" by the shock, exceeded the length of the Alps or the
Pyrenees.
As Hooke declared the favourite
hypothesis of the day ("that marine fossil bodies were to be referred to Noah's
flood") to be wholly untenable, he appears to have felt himself called upon to
substitute a diluvial theory of his own, and thus he became involved in
countless difficulties and contradictions. "During the great catastrophe," he
said, "there might have been a changing of that part which was before dry land
into sea by sinking, and of that which was sea into dry land by raising, and
marine bodies might have been buried in sediment beneath the ocean, in the
interval between the creation and the deluge." Then followed a disquisition on
the separation of the land from the waters, mentioned in Genesis: during which
operation some places of the shell of the earth were forced outwards, and others
pressed downwards or inwards, &c. His diluvial hypothesis very much resembled
that of Steno, and was entirely opposed to the fundamental principles professed
by him, that he would explain the former changes of the earth in a more
natural manner than others had done. When, in despite of this declaration,
he required a former "crisis of nature," and taught that earthquakes had become
debilitated, and that the Alp, Andes, and other chains, had been lifted up in a
few months, his machinery was as extravagant and visionary as that of his most
fanciful predecessors; and for this reason, perhaps, his whole theory of
earthquakes met with very undeserved neglect.
One of his contemporaries, the
celebrated naturalist, Ray, participated in the same desire to explain
geological phenomena, by reference to causes less hypothetical than those
usually resorted to. In his Essay on "Chaos and Creation" he proposed a system,
agreeing in its outline, and in many of its details, with that of Hooke; but his
knowledge of natural history enabled him to elucidate the subject with various
original observations. Earthquakes, he suggested, might have been the second
causes employed at the creation, in separating the land from the waters, and in
gathering the waters together into one place He mentions, like Hooke, the
earthquake of 1646, which had violently shaken the Andes for some hundreds of
leagues, and made many alterations therein. In assigning a cause for the general
deluge, he preferred a change in the earth's centre of gravity to the
introduction of earthquakes. Some unknown cause, he said, might have forced the
subterranean waters outwards, as was, perhaps, indicated by "the breaking up of
the fountains of the great deep."
Ray was one of the first of our
writers who enlarged upon the effects of running water upon the land, and of the
encroachment of the sea upon the shores. So important did he consider the agency
of these causes, that he saw in them an indication of the tendency of our system
to its final dissolution; and he wondered why the earth did not proceed more
rapidly towards a general submersion beneath the sea, when so much matter was
carried down by rivers, or undermined in the sea cliffs. We perceive clearly
from his writings, that the gradual decline of our system, and its future
consummation by fire, was held to be as necessary an article of faith by the
orthodox, as was the recent origin of our planet. His Discourses, like those of
Hooke, are highly interesting, as attesting the familiar association in the
minds of philosophers, in the age of Newton, of questions in physics and
divinity. Ray gave an unequivocal proof of the sincerity of his mind, by
sacrificing his preferment in the church, rather than take an oath against the
Covenanters, which he could not reconcile with his conscience. His reputation,
moreover, in the scientific world placed him high above the temptation of
courting popularity, by pandering to the physicotheological taste of his age. It
is, therefore, curious to meet with so many citations from the Christian fathers
and prophets in his essays on physical science-tc, find him in one page
proceeding by the strict rules of induction, to explain the former changes of
the globe, and in the next gravely entertaining the question, whether the sun
and stars, and the whole heavens shall be annihilated, together with the earth,
at the era of the grand conflagration.
Among the contemporaries of
Hooke and Ray, Woodward, a professor of medicine, had acquired the most
extensive information respecting the geological structure of the crust of the
earth. He had examined many parts of the British strata with minute attention;
and his systematic collection of specimens, bequeathed to the University of
Cambridge, and still preserved there as arranged by him, shews how far he had
advanced in ascertaining the order of superposition. From the great number of
facts collected by him we might have expected his theoretical views to be more
sound and enlarged than those of his contemporaries; but in his anxiety to
accommodate all observed phenomena to the scriptural account of the Creation and
Deluge, he arrived at most erroneous results. He conceived "the whole
terrestrial globe to have been taken to pieces and dissolved at the flood, and
the strata to have settled down from this promiscuous mass as any earthy
sediment from a fluid." In corroboration of these views, he insisted upon the
fact, that "marine bodies are lodged in the strata according to the order of
their gravity, the heavier shells in stone, the lighter in chalk, and so of the
rest." Ray immediately exposed the unfounded nature of this assertion, remarking
truly, that fossil bodies "are often mingled, heavy with light, in the same
stratum;" and he even went so far as to say, that Woodward "must have invented
the phenomena for the sake of confirming his bold and strange hypothesis"-a
strong expression from the pen of a contemporary.
At the same time Burnet
published his "Theory of the Earth." The title is most characteristic of the
age,-"The Sacred Theory of the Earth, containing an Account of the Original of
the Earth, and of all the general Changes which it hath already undergone, or is
to undergo, till the Consummation of all Things." Even Milton hall scarcely
ventured in his poem to indulge his imagination so freely in painting scenes of
the Creation and Deluge, Paradise and Chaos, as this writer, who set forth
pretensions to profound philosophy. He explained why the primeval earth enjoyed
a perpetual spring before the flood! shewed how the crust of the globe was
fissured by "the sun's rays," so that it burst, and thus the diluvial waters
were let loose from a supposed central abyss. Not satisfied with these themes,
he derived from the books of the inspired writers, and even from heathen
authorities, prophetic views of the future revolutions of the globe, gave a most
terrific description of the general conflagration, and proved that a new heaven
and a new earth will rise out of a second chaos-after which will follow
the blessed millennium.
The reader should be informed,
that according to the opinion of many respectable writers of that age, there was
good scriptural ground for presuming that the garden bestowed upon our first
parents was not on the earth itself, but above the clouds, in the middle region
between our planet and the moon. Burnet approaches with becoming gravity the
discussion of so important a topic. He was willing to concede that the
geographical position of Paradise was not in Mesopotamia, yet he maintained that
it was upon the earth, and in the southern hemisphere, near the equinoctial
line. Butler selected this conceit as a fair mark for his satire, when, amongst
the numerous accomplishments of Hudibras, he says-
He knew the seat of Paradise,
Could tell in what degree it lies;
And as he was disposed, could prove it
Below the moon or else above it.
Yet the same monarch, who is
said never to have slept without Butler's poem under his pillow, was so great an
admirer and patron of Burnet's book, that he ordered it to be translated from
the Latin into English. The style of the "Sacred Theory" was eloquent, and
displayed powers of invention of no ordinary stamp. It was, in fact, a fine
historical romance, as Buffon afterwards declared; but it was treated as a work
of profound science in the time of its author, and was panegyrized by Addison in
a Latin ode, while Steele praised it in the "Spectator," and Warton, in his
"Essay on Pope," discovered that Burnet united the faculty of judgment
with powers of imagination.
Another production of the same
school, and equally characteristic of the times, was that of Whiston, entitled,
"A New Theory of the Earth wherein the Creation of the World in six Days, the
Universal Deluge, and the General Conflagration, as laid down in the Holy
Scriptures, are shewn to be perfectly agreeable to Reason and Philosophy." He
was at first a follower of Burnet, but his faith in the infallibility of that
writer was shaken by the declared opinion of Newton, that there was every
presumption in astronomy against any former change in the inclination of the
earth's axis. This was a leading dogma in Burnet's system, though not original,
for it was borrowed from an Italian, Alessandro degli Alessandri, who had
suggested it in the beginning of the fifteenth century, to account for the
former occupation of the present continents by the sea. La Place has since
strengthened the arguments of Newton, against the probability of any former
revolution of this kind. The remarkable comet of 1680 was fresh in the memory of
every one, when Whiston first began his cosmological studies, and the principal
novelty of his speculations consisted in attributing the deluge to the near
approach to the earth of one of these erratic bodies. Having ascribed an
increase of the waters to this source, he adopted Woodward's theory, supposing
all stratified deposits to have resulted from the "chaotic sediment of the
flood." Whiston was one of the first who ventured to propose that the text of
Genesis should be interpreted differently from its ordinary acceptation, so that
the doctrine of the earth having existed long previous to the creation of man
might no longer be regarded as unorthodox. He had the art to throw an air of
plausibility over the most improbable parts of his theory, and seemed to be
proceeding in the most sober manner, and by the aid of mathematical
demonstration, to the establishment of his various propositions. Locke
pronounced a panegyric on his theory, commending him for having explained so
many wonderful and before inexplicable things. His book, as well as Burnet's,
was attacked and refuted by Keill. Like all who introduced purely hypothetical
causes to account for natural phenomena, he retarded the progress of truth,
diverting men from the investigation of the laws of sublunary nature, and
inducing them to waste time in speculations on the power of comets to drag the
waters of the ocean over the land-on the condensation of the vapours of their
tails into water, and other matters equally edifying.
John Hutchinson, who had been
employed by Woodward in making his collection of fossils, published afterwards,
in 1724, the first part of his "Moses's Principia," wherein he ridiculed
Woodward's hypothesis He and his numerous followers were accustomed to declaim
loudly against human learning, and they maintained that the Hebrew scriptures,
when rightly translated, comprised a perfect system of natural philosophy, for
which reason they objected to the Newtonian theory of gravitation.
Leibnitz, the great
mathematician, published his "Protogaea" in 1680. He imagined this planet to
have been originally a burning luminous mass, and that ever since its creation
it has been undergoing gradual refrigeration. Nearly all the matter of the earth
was at first encompassed by fire. When the outer crust had at length cooled down
sufficiently to allow the vapours to be condensed, they fell and formed a
universal ocean, investing the globe, and covering the loftiest mountains.
Further consolidation produced rents, vacuities, and subterranean caverns, and
the ocean, rushing in to fill them, was gradually lowered. The principal feature
of this theory, the gradual diminution of the original heat, and of an ancient
universal ocean, were adopted by Buffon and De Luc, and entered, under different
modifications, into a great number of succeeding systems.
Andrea Celsius, the Swedish
astronomer, published, about this time, his remarks on the gradual diminution of
the waters in the Baltic, which sea, he imagined, had been sinking from time
immemorial at the rate of forty-five inches in a century. His opinions gave rise
to a controversy which has lasted even to our own days, and to which we are
indebted for correct observations of a variety of facts concerning the gradual
filling up of the Baltic by fluviatile and marine sediment. Linnaeus favoured
the views of Celsius, because they fell in with his own notions concerning a
Paradise, where all the animals were created, and from whence they passed into
all other parts of the earth, as these became dry in succession.
In Germany, in the mean time,
Scheuchzer laboured to prove, in a work entitled the "Complaint of the Fishes,"
(1708,) that the earth had been remodelled at the deluge. Pluche also, in 1732,
wrote to the same effect, while Holbach, in 1753, after considering the various
attempts to refer all the ancient formations to the Noachian flood, exposed the
insufficiency of the cause.
We return with pleasure to the
geologists of Italy, who preceded, as we before saw, the naturalists of other
countries in their investigations into the ancient history of the earth, and who
still maintained a decided preeminence. They refuted and ridiculed the
physicotheological systems of Burnet, Whiston, and Woodward, while Vallisneri,
in his comments on the Woodwardian theory, remarked how much the interests of
religion as well as those of sound philosophy had suffered, by perpetually
mixing up the sacred writings with questions in physical science. The works of
this author were rich in original observations. He attempted the first general
sketch of the marine deposits of Italy, their geographical extent and most
characteristic organic remains. In his treatise "On the Origin of Springs," he
explained their dependence on the order, and often on the dislocations of the
strata, and reasoned philosophically against the opinions of those who regarded
the disordered state of the earth's crust as exhibiting signs of the wrath of
God for the sins of man. He found himself under the necessity of contending in
his preliminary chapter against St. Jerome, and four other principal
interpreters of scripture, besides several professors of divinity, "that springs
did not flow by subterranean syphons and cavities from the sea upwards, losing
their saltness in the passage," for this theory had been made to rest on the
infallible testimony of Holy Writ.
Although reluctant to
generalize on the rich materials accumulated in his travels, Vallisneri had been
so much struck with the remarkable continuity of the more recent marine strata,
from one end of Italy to the other, that he came to the conclusion that the
ocean formerly extended over the whole earth, and abode there for a long time.
This opinion, however untenable, was a great step beyond Woodward's diluvian
hypothesis, against which Vallisneri, and after him all the Tuscan geologists,
uniformly contended, while it was warmly supported by the members of the
Institute of Bologna.
Among others of that day,
Spada, a priest of Grezzana, in 1737, wrote to prove that the petrified marine
bodies near Verona were not diluviant. Mattani drew similar inference, from the
shells of Volterra, and other places; while Costantini, on the other hand, whose
observations on the valley of the Brenta and other districts were not without
value, undertook to vindicate the truth of the deluge, as also to prove that
Italy had been peopled by the descendants of Japhet. Lazzoro Moro, in his work
(published in 1740), "On the Marine Bodies which are found in the Mountains,"
attempted to apply the theory of earthquakes, as expounded by Strabo, Pliny, and
other ancient authors, with whom he was familiar, to the geological phenomena
described by Vallisnerill. His attention was awakened to the elevating power of
subterranean forces, by a remarkable phenomenon which happened in his own time,
and which had also been noticed by Vallisncri in his letters. A new island rose
in 1707, from a deep part of the sea near Santorino in the Mediterranean, during
continued shocks of an earthquake, and increasing rapidly in size, grew in less
than a month to be half a mile in circumference, and about twenty-five feet
above high-water mark. It was soon afterwards covered by volcanic ejections, but
when first examined it was found to be a white rock, bearing on its surface
living oysters and crustacea. In order to ridicule the various theories then in
vogue, Moro ingeniously supposes the arrival on this new isle of a party of
naturalists ignorant of its recent origin. One immediately points to the marine
shells, as proofs of the universal deluge; another argues, that they demonstrate
the former residence of the sea upon the mountains; a third dismisses them as
mere sports of nature; while a fourth affirms, that they were born and
nourished within the rock in ancient caverns, into which salt water had been
raised in the shape of vapour, by the action of subterranean heat.
Moro pointed with great
judgment to the faults and dislocations of the strata described by
Vallisneri, in the Alps and other chains, in confirmation of his doctrine, that
the continents had been heaved up by subterranean movements. He objected, on
solid grounds, to the hypotheses of Burnet and of Woodward; yet he ventured so
far to disregard the protest of Vallisneri, as to undertake the adaptation of
every part of his own system to the Mosaic account of the creation. On the third
day, he said the globe was every where covered to the same depth by fresh water,
and when it pleased the Supreme Being that the dry land should appear, volcanic
explosions broke up the smooth and regular surface of the earth composed of
primary rocks. These rose in mountain masses above the waves, and allowed melted
metals and salts to ascend through fissures. The sea gradually acquired its
saltness from volcanic exhalations, and, while it became more circumscribed
in area, increased in depth. Sand and ashes ejected by volcanoes were regularly
disposed along the bottom of the ocean and formed the secondary strata, which in
their turn were lifted up by earthquakes, We shall not attempt to follow him in
tracing the progress of the creation of vegetables, and animals on the other
days of creation; but, upon the whole, we may remark that few of the old
cosmological theories had been conceived with so little violation of known
analogies.
The style of Moro was extremely
prolix, and, like Hutton, who, at a later period, advanced many of the same
views, he stood in need of an illustrator. The Scotch geologist was not more
fortunate in the advocacy of Playfair, than was Moro in numbering amongst his
admirers Cirillo Generelli, who, nine years afterwards, delivered at a sitting
of Academicians at Cremona a spirited exposition of his theory. This learned
Carmelitan friar does not pretend to have been an original observer, but he had
studied sufficiently to be enabled to confirm the opinions of Moro by arguments
from other writers; and his selection of the doctrines then best established is
so judicious, that we shall present a brief abstract of them to our readers, as
illustrating the state of geology in Europe, and in Italy in particular, before
the middle of the last century. The bowels of the earth, says he, have carefully
preserved the memorials of past events, and this truth the marine productions so
frequent in the hills attest. From the reflections of Lazzaro Moro we may assure
ourselves, that these are the effects of earthquakes in past times, which have
changed vast spaces of sea into terra firma, and inhabited lands into seas. In
this, more than in any other department of physics, are observations and
experiments indispensable, and we must diligently consider facts. The land is
known, wherever we make excavations, to be composed of different strata or soils
placed one above the other, some of sand, some of rock, some of chalk, others of
marl, coal, pumice, gypsum, lime, and the rest. These ingredients are sometimes
pure, and sometimes confusedly intermixed. Within are often imprisoned different
marine fishes like dried mummies, and more frequently shells, crustacea, corals,
plants, &c., not only in Italy, but in France, Germany, England, Africa, Asia,
and America. Sometimes in the lowest sometimes in the loftiest beds of the
earth, some upon the mountains some in deep mines, others near the sea, and
others hundreds of miles distant from it. But there are in some districts rocks,
wherein no marine bodies are found. The remains of animals consist chiefly of
their more solid parts, and the most rocky strata must have been soft when such
exuviae were inclosed in them. Vegetable productions are found in different
states of maturity, indicating that they were imbedded in different seasons.
Elephants, elks, and other terrestrial quadrupeds, have been found in England
and elsewhere, in superficial strata, never covered by the sea. Alternations are
rare, yet not without example, of marine strata, and those which contain marhy
and terrestrial productions. Marine animals are arranged in the subterraneous
beds with admirable order, in distinct groups, oysters here, dentalia, or corals
there, &c., as now, according to Marsilli, on the shores of the Adriatic. We
must abandon the doctrine once so popular, that organized fossils have not been
derived from living beings, and we cannot account for their present position by
the ancient theory of Strato, nor by that of Leibnitz, nor by the universal
deluge, as explained by Woodward and others, "nor is it reasonable to call the
Deity capriciously upon the stage, and to make him work miracles, for the sake
of confirming our preconceived hypotheses."-"I hold in utter abomination, most
learned Academicians! those systems which are built with their foundations in
the air, and cannot be propped up without a miracle; and I undertake, with the
assistance of Moro, to explain to you, how these marine animals were transported
into the mountains by natural causes." A brief abstract then follows of Moro's
theory, by which, says Generelli, we may explain all the phenomena, as
Vallisneri so ardently desired, "without violence, without fictions, without
hypotheses, without miracles." The Carmelitan then proceeds to struggle
against an obvious objection to Moro's system, considered as a method of
explaining the revolutions of the earth, naturally. If earthquakes have
been the agents of such mighty changes, how does it happen that their effects
since the times of history have been so inconsiderable? This same difficulty
had, as we have seen, presented itself to Hooke, half a century before, and
forced him to resort to a former "crisis of nature;" but Generelli defended his
position by shewing how numerous were the accounts of eruptions and earthquakes,
of new islands, and of elevations and subsidences of land, and yet how much
greater a number of like events must have been unattested and unrecorded during
the last six thousand years. He also appealed to Vallisneri as an authority to
prove that the mineral masses containing shells bore, upon the whole, but a
small pro portion to those rocks which were destitute of organic remains; and
the latter, says the learned monk, might have been created as they now exist,
in the beginning. He then describes the continual waste of mountains and
continents, by the action of rivers and torrents, and concludes with these
eloquent and original observations: " Is it possible that this waste should have
continued for six thousand, and perhaps a greater number of years, and
that the mountains should remain so great, unless their ruins have been
repaired? Is it credible that the Author of nature should have founded the world
upon such laws, as that the dry land should for ever be growing smaller, and at
last become wholly submerged beneath the waters? Is it credible that, amid so
many created things, the mountains alone should daily diminish in number and
bulk, without there being any repair of their losses? This would be contrary to
that order of Providence which is seen to reign in all other things in the
universe. Wherefore I deem it just to conclude, that the same cause which, in
the beginning of time, raised mountains from the abyss, has, down to the present
day, continued to produce others, in order to restore from time to time the
losses of all such as sink down in different places, or are rent asunder, or in
other ways suffer disintegration. If this be admitted, we can easily understand
why there should now be found upon many mountains so great a number of crustacea
and other marine animals."
The reader will remark, that
although this admirable essay embraces so large a portion of the principal
objects of geological research, it makes no allusion to the extinction of
certain classes of animals; and it is evident that no opinions on this head had,
at that time, gained a firm footing in Italy. That Lister and other English
naturalists should long before have declared in favour of the loss of species,
while Scilla and most of his countrymen hesitated, was natural, since the
Italian museums were filled with fossil shells, belonging to species of which a
great portion did actually exist in the Mediterranean, whereas the English
collectors could obtain no recent species from their own strata.
The weakest point in Moro's
system consisted in deriving all the stratified rocks from volcanic
ejections, an absurdity which his opponents took care to expose, especially Vito
Amici#. Moro seems to have been misled by his anxious desire to represent the
formation of secondary rocks as having occupied an extremely short period, while
at the same time he wished to employ known agents in nature. To imagine
torrents, rivers, currents, partial floods, and all the operations of moving
water, to have gone on exerting an energy many thousand times greater than at
present, would have appeared preposterous and incredible, and would have
required ahundred violent hypotheses; but we are so unacquainted with the true
sources of subterranean disturbances, that their former violence may in theory
be multiplied indefinitely, without its being possible to prove the same
manifest contradiction or absurdity in the conjecture. For this reason, perhaps,
Moro preferred to derive the materials of the strata from volcanic ejections,
rather than from transportation by running water.
Marsilli, in the work above
alluded to by Generelli, had been prompted to institute inquiries into the bed
of the Adriatic, by discovering in the territory of Parma, (what Spada had
observed near Verona, and Schiavo in Sicily,) that fossil shells were not
scattered through the rocks at random, but disposed in regular order, according
to families. But with a view of throwing further light upon these questions,
Donati, in 1750, undertook a more extensive investigation of the Adriatic, and
discovered, by numerous soundings, that deposits of sand, marl, and tufaceous
incrustations, most strictly analogous to those of the Subapennine hills, were
in the act of accumulating there. He ascertained that there were no shells in
some of the submarine tracts, while in other places they lived together in
families, particularly the genera Arca, Pecten, Venus, Murex, and some others. A
contemporary naturalist, Baldassali, had shewn the same grouping of organic
remains in the tertiary marls of the Sienese territory.
Buffon first made known his
theoretical views concerning the former changes of the earth in his Natural
History, published in 1749. His opinions were directly opposed to the systems of
Hooke, Ray, and Moro, for he attributed no influence whatever to subterranean
movements and volcanoes, but returned to the universal ocean of Leibnitz. By
this aqueous envelope the highest mountains were once covered. Marine currents
then acted violently, and formed horizontal strata, by washing away land in some
parts, and depositing it in others; they also excavated deep submarine valleys.
He was greatly at a loss for some machinery to depress the level of the ocean,
and cause the land to be left dry. He therefore speculated on the possibility of
subterranean caverns having opened, into which the water entered, so that he
involuntarily approximated to Hooke's theory of subsidences by earthquakes.
Buffon had never profited, like Moro, by the observations of Vallisneri, or he
never could have imagined that the strata were generally horizontal, and that
those which contain organic remains had never been disturbed since the era of
their formation He was conscious of the great power annually exerted by rivers
and marine currents in transporting earthy materials to lower levels, and he
even contemplated the period when they would destroy all the present continents.
Although in geology he was not an original observer, his genius enabled him to
render his hypothesis attractive; and by the eloquence of his style, and
the boldness of his speculations, he awakened curiosity and provoked a spirit of
inquiry amongst his countrymen..
Soon after the publication of
his "Natural History," in which was included his "Theory of the Earth," he
received an official letter (dated January, 1751), from the Sorbonlle or Faculty
of Theology in Paris, informing him that fourteen propositions in his works "
were reprehensible and contrary to the creed of the church." The first of these
obnoxious passages, and the only one relating to geology, was as follows. "The
waters of the sea have produced the mountains and valleys of the land-the waters
of the heavens, reducing all to a level, will at last deliver the whole
land over to the sea, and the sea, successively prevailing over the land, will
leave dry new continents like those which we inhabit." Buffoll was invited l)y
the College in very courteous terms, to send in an explanation, or rather a
recantation, of his unorthodox opinions. To this he submitted, and a general
assembly of the Faculty having approved of his "Declaration," he was
required to publish it in his next work. The document begins with these words-"I
declare that I had no intention to contradict the text of Scripture; that I
believe most firmly all therein related about the creation, both as to order of
time and matter of fact; and I abandon everything in my book
respecting the formation of the earth, and generally all which may be
contrary to the narration of Moses."
The grand principle which
Buffon was called upon to renounce was simply this, "that the present mountains
and valleys of the earth are due to secondary causes, and that the same causes
will in time destroy all thc continents, hills and valleys, and reproduce others
like them." Now, whatever may be the defects of many of his views, it is no
longer controverted, that the present continents are of secondary origin. The
doctrine is as firmly established as the earth's rotation on its axis; and that
the land now elevated above the level of the sea will not endure for ever, is an
opinion which gains ground daily, in proportion as we enlarge our experience of
the changes now in progress.
Hollmann was the author of a
Memoir in the Transactions of the Royal Society of Gottingen in 1753, wherein he
proposed an hypothesis closely corresponding to the opinions of Buffon; and
devoted the rest of his work to refuting certain diluvial theories of his day.
Targioni, in his voluminous
"Travels in Tuscany, 1751 and 1754," laboured to fill up the sketch of the
geology of that region, left by Steno sixty years before. Notwithstanding a want
of arrangement and condensation in his memoirs, they contained a rich store of
faithful observations. He has not indulged in many general views, but in regard
to the origin of valleys he was opposed to the theory of Buffon, who attributed
them principally to submarine currents. The Tuscan naturalist laboured to shew
that both the larger and smaller valleys of the Apennines were excavated by
rivers, and floods, caused by the bursting of the barriers of lakes, after the
retreat of the ocean. He also maintained that the elephants, and other
quadrupeds so frequent in the lacustrine and alluvial deposits of Italy, had
inhabited that peninsula; and had not been transported thither, as some had
conceived, by Hannibal, or the Romans, nor by what they were pleased to term "a
catastrophe of nature."
Arduino, in his memoirs on the
mountains of Padua, Vicenza, and Veronat first recognized the distinction
between primary, secondary, and tertiary rocks, and shewed that in those
districts there had been a succession of submarine volcanic eruptions. ln the
very same year the treatise of Lehman, a German mineralogist, and director of
the Prussian mines, appeared, who also divided mountains into three classes: the
first, which were formed with the world and prior to the creation of animals,
and which contained no fragments of other rocks; the second class, of mountains
which resulted from the partial destruction of the primary rocks by a general
revolution; and the third class, which resulted from local revolutions, and, in
part, from the Noachian deluge.
In the following year (1760)
the Rev. John Michell, Woodwardian Professor of Mineralogy at Cambridge,
published in the Philosophical Transactions, an Essay on the Cause and Phenomena
of Earthquakes. His attention had been drawn to this subject by the great
earthquake of Lisbon in 1755. He advanced many original and philosophical views
respecting the propagation of subterranean movements, and the caverns and
fissures wherein steam might be generated. In order to point out the application
of his theory to the structure of the globe, he was led to describe the
arrangement and disturbance of the strata, their usual horizontality in low
countries, and their contortions and fractured state in the neighbourhood of
mountain chains. He also explained, with surprising accuracy, the relations of
the central ridges of older rocks to the "long narrow slips of similar earths,
stones, and minerals," which are parallel to these ridges. In his
generalizations, derived in great part from his own observations on the
geological structure of Yorkshire, he anticipated many of the views more fully
developed by later naturalists.
Michell's papers were entirely
free from all physicotheological disquisitions, but some of his contemporaries
were still earnestly engaged in defending or impugning the Woodwardian
hypothesis. We find many of these writings referred to by Catcott, an
Hutchinsonian, who published a "Treatise on the Deluge" in 1761. He laboured
particularly to refute an explanation offered by his contemporary, Bishop
Clayton, of the Mosaic writings. That prelate had declared that the Deluge could
not be literally true, save in respect to that part where Noah lived before the
flood." Catcott insisted on the universality of the deluge, and referred to
traditions of inundations mentioned by ancient writers, or by travellers in the
East Indies, China, South America, and other countries. This part of his book is
valuable, although it is not easy to see what bearing the traditions have, if
admitted to be authentic, on the Bishop's argument, since no evidence is adduced
to prove that the catastrophes were contemporaneous events, while some of them
are expressly represented by ancient authors to have occurred in succession.
The doctrines of Arduino, above
adverted to, were afterwards confirmed by Fortis and Desmarest, in their travels
in the same country, and they, as well as Baldassari, laboured to complete the
history of the Subapennine strata. In the work of Odoardi, there was also a
clear argument in favour of the distinct ages of the older Apennine strata, and
the Subapennine formations of more recent origin. He pointed out that the strata
of these two groups were unconformable, and must have been the deposits of
different seas at distant periods of time.
A history of the new islands by
Raspe, an Hanoverian, appeared in l763, in Latin. In this work, all the
authentic accounts of earthquakes which had produced permanent changes on the
solid parts of the earth were collected together and examined with judicious
criticism. The best systems which had been proposed concerning the ancient
history of the globe, both by ancient and modern writers, are reviewed. The
merits and defects of the systems of Hooke, Ray, Moro, Buffon, and others, are
fairly estimated. Great admiration is expressed for the hypothesis of Hooke, and
his explanation of the origin of the strata is shewn to have been more correct
than Moro's, while their theory of the effects of earthquakes was the same.
Raspe had not seen Michell's memoir, and his views concerning the geological
structure of the earth were perhaps less enlarged, yet he was able to add many
additional arguments in favour of Hooke's theory, and to render it, as he said,
a nearer ayproach to what Hooke would have written had he lived in later times.
As to the periods wherein all the earthquakes happened, to which we owe the
elevation of various parts of our continents and islands, Raspe says he pretends
not to assign their duration, still less to defend Hooke's suggestion, that the
convulsions almost all took place during the Noachian deluge. He adverts to the
apparent indications of the former tropical heat of the climate of Europe, and
the changes in the species of animals and plants, as among the most obscure and
difficult problems in geology. In regard to the islands raised from the sea,
within the times of history or tradition, he declares that some of them were
composed of strata containing organic remains, and that they were not, as Buffon
had asserted, made of mere volcanic matter. His work concludes with an eloquent
exhortation to naturalists, to examine the isles which rose in 1707, in the
Grecian Archipelago, and in 1720 in the Azores, and not to neglect such splendid
opportunities of studying nature "in the act of parturition." That Hooke's
writings should have been neglected for more than half a century, was matter of
astonishment to Raspe; but, it is still more wonderful that his own luminous
exposition of that theory should, for more than another half century, have
excited so little interest.
Gustavus Brander published, in
1766, his "Fossilia Hantoniensia," containing excellent figures of fossil shells
from the more modern marine strata of our island. "Various opinions," he says in
the preface, "had been entertained concerning the time when and how these bodies
became deposited. Some there are who conceive that it might have been effected
in a wonderful length of time by a gradual changing and shifting of the sea, &c.
But the most common cause assigned is that of "the deluge." This conjecture, he
says, even if the universality of the flood be not called in question, is purely
hypothetical. In his opinion fossil animals and testacea were, for the most
part, of unknown species, and of such as were known, the living analogues now
belonged to southern latitudes.
Soldani applied successfully
his knowledge of zoology to illustrate the history of stratified masses. He
explained that microscopic testacea and zoophytes inhabited the depths of the
Mediterranean, and that the fossil species were, in like manner, found in those
deposits wherein the fineness of their particles, and the absence of pebbles,
implied that they were accumulated in a deep sea far from any shore. This author
first remarked the alternation of marine and fresh water strata in the Paris
basin. A lively controversy arose between Fortis and another Italian naturalist,
Testa, concerning the fish of Monte Bolca, in 1793. Their letters, written with
great spirit and elegance, shew that they were aware that a large proportion of
the Subapennine shells were identical with living species, and some of them with
species now living in the torrid zone. Fortis conectured that when the volcanos
of the Vicentin were burning, the waters of the Adriatic had a higher
temperature; and in this manner, he said that the shells of warmer regions may
once have peopled their own seas. But Testa was disposed to think, that these
species of testacea were still common to their own and to equinoctial seas, for
many, he said, once supposed to be confined to hotter regions, had been
afterwards discovered in the Mediterranean.
While these Italian
naturalists, together with Cortesi and Spallanzani, were busily engaged in
pointing out the analogy between the deposits of modern and ancient seas, and
the habits and arrangement of their organic inhabitants, and while some progress
was making in the same country, in investigating the ancient and modern volcanic
rocks, the most original observers among the English and German writers,
Wallerius and Whitehurst, were wasting their strength in contending, according
to the old Woodwardian hypothesis, that all the strata were formed by the
Noachian deluge. But Whitehurst's description of the rocks of Derbyshire was
most faithful, and he atoned for false theoretical views, by providing data for
their refutation.
The mathematician, Boscovich,
of Ragusa in Dalmatia, in his letters, published at Venice in 1772, declared his
persuasion, that the effects of earthquakes, although insensible in the course
of a few years, do nevertheless raise, from time to time, and let down different
parts of the crust of our globe, and sometimes fold and twist them. Like Hooke,
Ray, and Moro, he conceived the subterranean movements to have acted with
greater energy at former epochs.
Towards the close of the
eighteenth century, the idea of distinguishing the mineral masses on our globe
into separate groups, and studying their relations, began to be generally
diffused. Pallas and Saussure were among the most celebrated whose labours
contributed to this end. After an attentive examination of the two great
mountain chains of Siberia, Pallas announced the result that the granitic rocks
were in the middle, the schistose at their sides, and the limestones again on
the outside of these; and this he conceived would prove a general law in the
formation of all chains composed chiefly of primary rocks.
In his "Travels in Russia," in
1793 and 1794, he made many geological observations on the recent strata near
the Wolga and the Caspian and adduced proofs of the greater extent of the latter
sea at no distant era in the earth's history. His memoir on the fossil bones of
Siberia attracted attention to some of the most remarkable phenomena in geology.
He stated that he had found a rhinoceros entire in the frozen soil, with its
skin and flesh: an elephant, found afterwards in a mass of ice on the shore of
the north sea, removed all doubt as to the accuracy of so wonderful a discovery.
The subjects relating to
natural history which engaged the attention of Pallas were too multifarious to
admit of his devoting a large share of his labours exclusively to geology.
Saussure, on the other hand, employed the chief portion of his time in studying
the structure of the Alps and Jura, and he provided valuable data for those who
followed him. We cannot enter into the details of these observations, and he did
not pretend to have arrived at any general system. The few theoretical
observations which escaped from him are, like those of Pallas, mere
modifications of the old cosmological doctrines.
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