Chapter L: Formation of Coral Reefs (2)

It appears, therefore, premature to assert that there are no recent coral formations uplifted to great heights, for we are only beginning to be acquainted with the geological structure of the rocks of equatorial regions. Some of the upraised islands, such as Elizabeth and Queen Charlotte, in the Pacific, although placed in regions of atolls, are described by Captain Beechey and others as flat-topped, and exhibiting no traces of lagoons. In explanation of the fact, we may presume that after they had been sinking for ages, the descending movement was relaxed; and while it was in the course of being converted into an ascending one, the ground remained for a long season almost stationary, in which case the corals within the lagoon would build up to the surface, and reach the level already attained by those on the margin of the reef. In this manner the lagoon would be effaced, and the island acquire a flat summit.

It may, however, be thought strange that many examples have not been noticed of fringing reefs uplifted above the level of the sea. Mr. Darwin, indeed, cites one instance where the reef preserved, on dry land in the Mauritius, its peculiar moat-like structure; but they ought, he says, to be of rare occurrence, for in the case of atolls or of barrier or fringing reefs, the characteristic outline must usually be destroyed by denudation as soon as a reef begins to rise; since it is immediately exposed to the action of the breakers, and the large and conspicuous corals on the outer rim of the atoll or barrier are the first to be destroyed and to fall to the bottom of vertical and undermined cliffs. After slow and continued upheaval a wreck alone can remain of the original reef. If, therefore, says Mr. Darwin, "at some period as far in futurity as the secondary rocks are in the past, the bed of the Pacific with its atolls and barrier reefs should be converted into a continent, we may conceive that scarcely any or none of the existing reefs would be preserved, but only widely spread strata of calcareous matter derived from their wear and tear."[1136]

When it is urged in support of the objection before stated (p. 767), that the theory of atolls by subsidence implies the accumulation of calcareous formations 2000 or 3000 feet thick, it must be conceded that this estimate of the minimum density of the deposits is by no means exaggerated. On the contrary, when we consider that the space over which atolls are scattered in Polynesia and the Indian oceans may be compared to the whole continent of Asia, we cannot but infer from analogy that the differences in level in so vast an area have amounted, antecedently to subsidence, to 5000 or even a greater number of feet. Whatever was the difference in height between the loftiest and lowest of the original mountains or mountainous islands on which the different atolls are based, that difference must represent the thickness of coral which has now reduced all of them to one level. Flinders, therefore, by no means exaggerated the volume of the limestone, which he conceived to have been the work of coral animals; he was merely mistaken as to the manner in which they were enabled to build reefs in an unfathomed ocean.

But is it reasonable to expect, after the waste caused by denudation, that calcareous masses, gradually upheaved in an open sea, should retain such vast thicknesses? Or may not the limestones of the cretaceous and oolitic epochs, which attain in the Alps and Pyrenees a density of 3000 or 4000 feet, and are in great part made up of coralline and shelly matter, present us with a true geological counterpart of the recent coral reefs of equatorial seas?

Before we attach serious importance to arguments founded on negative evidence, and opposed to a theory which so admirably explains a great variety of complicated phenomena, we ought to remember that the upheaval to the height of 4000 feet of atolls in which the coralline limestone would be 4000 feet thick, implies, first, a slow subsidence of 4000 feet, and, secondly, an elevation of the same amount. Even if the reverse or ascending movement began the instant the downward one ceased, we must allow a great lapse of ages for the accomplishment of the whole operation. We must also assume that at the commencement of the period in question, the equatorial regions were as fitted as now for the support of reef-building zoophytes. This postulate would demand the continuance of a complicated variety of conditions throughout a much longer period than they are usually persistent in one place.

To show the difficulty of speculating on the permanence of the geographical and climatal circumstances requisite for the growth of reef-building corals, we have only to state the fact that there are no reefs in the Atlantic, off the west coast of Africa, nor among the islands of the Gulf of Guinea, nor in St. Helena, Ascension, the Cape Verdes, or St. Paul's. With the exception of Bermuda, there is not a single coral reef in the central expanse of the Atlantic, although in some parts the waves, as at Ascension, are charged to excess with calcareous matter. This capricious distribution of coral reefs is probably owing to the absence of fit stations for the reef-building polypifers, other organic beings in those regions obtaining in the great struggle for existence a mastery over them. Their absence, in whatever manner it be accounted for, should put us on our guard against expecting upraised reefs at all former geological epochs, similar to those now in progress.

_Lime, whence derived._--Dr. Maculloch, in his system of Geology, vol. i. p. 219, expressed himself in favor of the theory of some of the earlier geologists, that all limestones have originated in organized substances. If we examine, he says, the quantity of limestone in the primary strata, it will be found to bear a much smaller proportion to the siliceous and argillaceous rocks than in the secondary; and this may have some connexion with the rarity of testaceous animals in the ancient ocean. He farther infers, that in consequence of the operations of animals, "the quantity of calcareous earth deposited in the form of mud or stone is always increasing; and that as the secondary series far exceeds the primary in this respect, so a third series may hereafter arise from the depths of the sea, which may exceed the last in the proportion of its calcareous strata."

If these propositions went no farther than to suggest that every particle of lime that now enters into the crust of the globe, may possibly in its turn have been subservient to the purposes of life, by entering into the composition of organized bodies, I should not deem the speculation improbable; but, when it is hinted that lime may be an animal product combined by the powers of vitality from some simple elements, I can discover no sufficient grounds for such an hypothesis, and many facts militate against it.

If a large pond be made in almost any soil, and filled with rain water, it may usually become tenanted by testacea; for carbonate of lime is almost universally diffused in small quantities. But if no calcareous matter be supplied by waters flowing from the surrounding high grounds, or by springs, no tufa or shell-marl are formed. The thin shells of one generation of mollusks decompose, so that their elements afford nutriment to the succeeding races; and it is only where a stream enters a lake, which may introduce a fresh supply of calcareous matter, or where the lake is fed by springs, that shells accumulate and form marl.

All the lakes in Forfarshire which have produced deposits of shell-marl have been the sites of springs, which still evolve much carbonic acid, and a small quantity of carbonate of lime. But there is no marl in Loch Fithie, near Forfar, where there are _no springs_, although that lake is surrounded by these calcareous deposits, and although, in every other respect, the site is favorable to the accumulation of aquatic testacea.

We find those Charae which secrete the largest quantity of calcareous matter in their stems to abound near springs impregnated with carbonate of lime. We know that, if the common hen be deprived altogether of calcareous nutriment, the shells of her eggs will become of too slight a consistency to protect the contents; and some birds eat chalk greedily during the breeding season.

If, on the other hand, we turn to the phenomena of inorganic nature, we observe that, in volcanic countries, there is an enormous evolution of carbonic acid, either free, in a gaseous form, or mixed with water; and the springs of such districts are usually impregnated with carbonate of lime in great abundance. No one who has travelled in Tuscany, through the region of extinct volcanos and its confines, or who has seen the map constructed by Targioni (1827), to show the principal sites of mineral springs, can doubt, for a moment, that if this territory was submerged beneath the sea, it might supply materials for the most extensive coral reefs. The importance of these springs is not to be estimated by the magnitude of the rocks which they have thrown down on the slanting sides of hills, although of these alone large cities might be built, nor by a coating of travertin that covers the soil in some districts for miles in length. The greater part of the calcareous matter passes down in a state of solution to the sea, and in all countries the rivers which flow from chalk and other marly and calcareous rocks carry down vast quantities of lime into the ocean. Lime is also one of the component parts of augite and other volcanic and hypogene minerals, and when these decompose is set free, and may then find its way in a state of solution to the sea.

The lime, therefore, contained generally in sea water, and secreted so plentifully by the testacea and corals of the Pacific, may have been derived either from springs rising up in the bed of the ocean, or from rivers fed by calcareous springs, or impregnated with lime derived from disintegrated rocks, both volcanic and hypogene. If this be admitted, the greater proportion of limestone in the more modern formations as compared to the most ancient, will be explained, for springs in general hold no argillaceous, and but a small quantity of siliceous matter in solution, but they are continually subtracting calcareous matter from the inferior rocks. The constant transfer, therefore, of carbonate of lime from the lower or older portions of the earth's crust to the surface, must cause at all periods and throughout an indefinite succession of geological epochs, a preponderance of calcareous matter in the newer as contrasted with the older formations.

THE END.

CONCLUDING REMARKS.

In the concluding chapters of the first book, I examined in detail a great variety of arguments which have been adduced to prove the distinctness of the state of the earth's crust at remote and recent epochs. Among other supposed proofs of this distinctness, the dearth of calcareous matter, in the ancient rocks above adverted to, might have been considered. But it would have been endless to enumerate all the objections urged against those geologists who represent the course of nature at the earliest periods as resembling in all essential circumstances the state of things now established. We have seen that, in opposition to this doctrine, a strong desire has been manifested to discover in the ancient rocks the signs of an epoch when the planet was uninhabited, and when its surface was in a chaotic condition and uninhabitable. The opposite opinion, indeed, that the oldest of the rocks now visible may be the last monuments of an antecedent era in which living beings may already have peopled the land and water, has been declared to be equivalent to the assumption that there never was a beginning to the present order of things.

With equal justice might an astronomer be accused of asserting that the works of creation extended throughout _infinite_ space, because he refuses to take for granted that the remotest stars now seen in the heavens are on the utmost verge of the material universe. Every improvement of the telescope has brought thousands of new worlds into view; and it would, therefore, be rash and unphilosophical to imagine that we already survey the whole extent of the vast scheme, or that it will ever be brought within the sphere of human observation.

But no argument can be drawn from such premises in favor of the infinity of the space that has been filled with worlds; and if the material universe has any limits, it then follows, that it must occupy a minute and infinitesimal point in infinite space.

So if, in tracing back the earth's history, we arrive at the monuments of events which may have happened millions of ages before our times, and if we still find no decided evidence of a commencement, yet the arguments from analogy in support of the probability of a beginning remain unshaken; and if the past duration of the earth be finite, then the aggregate of geological epochs, however numerous, must constitute a mere moment of the past, a mere infinitesimal portion of eternity.

It has been argued, that, as the different states of the earth's surface, and the different species by which it has been inhabited have all had their origin, and many of them their termination, so the entire series may have commenced at a certain period. It has also been urged, that, as we admit the creation of man to have occurred at a comparatively modern epoch--as we concede the astonishing fact of the first introduction of a moral and intellectual being--so also we may conceive the first creation of the planet itself.

I am far from denying the weight of this reasoning from analogy; but, although it may strengthen our conviction, that the present system of change has not gone on from eternity, it cannot warrant us in presuming that we shall be permitted to behold the signs of the earth's origin, or the evidences of the first introduction into it of organic beings. We aspire in vain to assign limits to the works of creation in _space_, whether we examine the starry heavens, or that world of minute animalcules which is revealed to us by the microscope. We are prepared, therefore, to find that in time also the confines of the universe lie beyond the reach of mortal ken. But in whatever direction we pursue our researches, whether in _time_ or space, we discover everywhere the clear proofs of a Creative Intelligence, and of His foresight, wisdom, and power.

As geologists, we learn that it is not only the present condition of the globe which has been suited to the accommodation of myriads of living creatures, but that many former states also have been adapted to the organization and habits of prior races of beings. The disposition of the seas, continents, and islands, and the climates, have varied; the species likewise have been changed; and yet they have all been so modelled, on types analogous to those of existing plants and animals, as to indicate, throughout, a perfect harmony of design and unity of purpose. To assume that the evidence of the beginning or end of so vast a scheme lies within the reach of our philosophical inquiries, or even of our speculations, appears to be inconsistent with a just estimate of the relations which subsist between the finite powers of man and the attributes of an Infinite and Eternal Being.

FOOTNOTES:

[1] Essays on the Philosophy of the Hindoos.

[2] Institutes of Hindoo Law, or the Ordinances of Menu, from the
Sanscrit, translated by Sir William Jones, 1796.

[3] Menu, Inst. c. i. 66, and 67.

[4] Herodot. Euterpe, 12.

[5] A Persian MS. copy of the historian Ferishta, in the library
of the East India Company, relating to the rise and progress of
the Mahomedan empire in India, was procured by Colonel Briggs from
the library of Tippoo Sultan in 1799; which has been referred to
at some length by Dr. Buckland. (Geol. Trans. 2d Series, vol. ii.
part iii. p. 389.)

[6] See Davis on "The Chinese," published by the Soc. for the
Diffus. of Use. Know. vol. i. pp. 137, 147.

[7] Humboldt et Bonpland, Voy. Relat. Hist. vol. i. p. 30.

[8] Prichard's Egypt. Mythol. p. 177.

[9] Plut. de Defectu Oraculorum, cap. 12. Censorinus de Die
Natali. See also Prichard's Egypt. Mythol. p. 182.

[10] Prichard's Egypt. Mythol. p. 182.

[11] Prichard's Egypt. Mythol. p. 193.

[12] Plato's Timaeus.

[13] Ovid's Metamor. lib. 15.

[14] Eluvie mons est deductus in aequor, v. 267. The meaning of
this last verse is somewhat obscure; but, taken with the context,
may be supposed to allude to the abrading power of floods,
torrents, and rivers.

[15] The impregnation from new mineral springs, caused by
earthquakes in volcanic countries, is perhaps here alluded to.

[16] That is probably an allusion to the escape of inflammable
gas, like that in the district of Baku, west of the Caspian; at
Pietramala, in the Tuscan Apennines; and several other places.

[17] Many of those described seem fanciful fictions, like the
virtue still so commonly attributed to mineral waters.

[18] Raspe, in a learned and judicious essay (De Novis Insulis,
cap. 19), has made it appear extremely probable that all the
traditions of certain islands in the Mediterranean having at some
former time frequently shifted their positions, and at length
become stationary, originated in the great change produced in
their form by earthquakes and submarine eruptions, of which there
have been modern examples in the new islands raised in the time
of history. When the series of convulsions ended, the island was
said to become fixed.

[19] It is not inconsistent with the Hindoo mythology to suppose
that Pythagoras might have found in the East not only the system
of universal and violent catastrophes and periods of repose in
endless succession, but also that of periodical revolutions,
effected by the continued agency of ordinary causes. For Brahma,
Vishnu, and Siva, the first, second, and third persons of the
Hindoo triad, severally represented the Creative, the Preserving,
and the Destroying powers of the Deity. The coexistence of these
three attributes, all in simultaneous operation, might well
accord with the notion of perpetual but partial alterations
finally bringing about a complete change. But the fiction
expressed in the verses before quoted from Menu of eternal
vicissitudes in the vigils and slumbers of Brahma seems
accommodated to the system of great general catastrophes followed
by new creations and periods of repose.

[20] Meteor. lib. i. cap. 12.

[21] De Die Nat.

[22] Lib. ii. cap. 14, 15, and 16.

[23] Lib. ii. cap. 14, 15, and 16.

[24] Omne ex integro animal generabitur, dabiturque terris homo
inscius scelerum.--Quaest. Nat. iii. c. 29.

[25] This author was Regius Professor of Syriac and Arabic at
Paris, where, in 1685, he published a Latin translation of many
Arabian MSS. on different departments of philosophy. This work
has always been considered of high authority.

[26] Gerbanitae docebant singulos triginta sex mille annos
quadringentos, viginti quinque bina ex singulis animalium
speciebus produci, marem scilicet ac feminam ex quibus animalia
propagantur, huncque inferiorem incolunt orbem. Absoluta autem
coelestium orbium circulatione, quae illo annorum conficitur
spatio, iterum alia producuntur animalium genera et species,
quemadmodum et plantarum aliarumque rerum, et primus destruitur
ordo, sicque in infinitum producitur.--Histor. Orient Suppl. per
Abrahamum Ecchellensem, Syrum Maronitam, cap. 7. et 8. ad calcem
Chronici Orientali. Parisiis, e Typ. Regia. 1685, fol.

I have given the punctuation as in the Paris edition, there being
no comma after quinque; but, at the suggestion of M. de Schlegel,
I have referred the number twenty-five to the period of years,
and not to the number of pairs of each species created at one
time, as I had done in the two first editions. Fortis inferred
that twenty-five new _species_ only were created at a time; a
construction which the passage will not admit. Mam. sur l'Hist.
Nat. de l'Italie, vol. i. p. 202.

[27] "Quod enim hoc attollitur aut subsidit, et vel inundat
quaedam loca, vel ab iis recedit, ejus rei causa non est, quod
alia aliis sola humiliora sint aut altiora; sed quod idem solum
modo attollitur modo deprimitur, simulque etiam modo attollitur
modo deprimitur, mare: itaque vel exundat vel in suum redit
locum."

Postea, p. 88. "Restat, ut causam adscribamus solo, sive quod
mari subest sive quod inundatur; potius tamen ei quod mari
subest. Hoc enim multo est mobilius, et quod ob humiditatem
celerius multari possit."--Strabo, Geog. Edit. Almelov. Amst.
1707, lib. 1.

[28] _Volcanic eruptions_, eruptiones flatuum, in the Latin
translations, and in the original Greek, [Greek: anaphysemata],
gaseous eruptions? or _inflations_ of land?--Ibid. p. 93.

[29] Strabo, lib. vi. p. 396.

[30] Book iv.

[31] L. vi. ch. xiii.

[32] Mod. Univ. Hist. vol. ii. chap. iv. section iii.

[33] Montes quandoque fiunt ex causa essentiali, quandoque ex
causa accidentali. Ex essentiali causa, ut ex vehementi motu
terrae elevatur terra, et fit mons. Accidentali, &c.--De
Congelatione Lapidum, ed. Gedani, 1682.

[34] Von Hoff, Geschichte der Veranderungen der Erdoberflache,
vol. i. p. 406, who cites Delisle, bey Hismann Welt- und
Volkergeschichte. Alte Geschichte 1^{ter} theil, s. 234.--The
Arabian persecutions for heretical dogmas in theology were often
very sanguinary. In the same ages wherein learning was most in
esteem, the Mahometans were divided into two sects, one of whom
maintained that the Koran was increate, and had subsisted in the
very essence of God from all eternity; and the other, the
Motazalites, who, admitting that the Koran was instituted by God,
conceived it to have been first made when revealed to the Prophet
at Mecca, and accused their opponents of believing in two eternal
beings. The opinions of each of these sects were taken up by
different caliphs in succession, and the followers of each
sometimes submitted to be beheaded, or flogged till at the point
of death, rather than renounce their creed.--Mod. Univ. Hist.
vol. ii. ch. iv.

[35] Koran, chap. xli.

[36] Sale's Koran, chap. xi. see note.

[37] Ibid.

[38] Kossa, appointed master to the Caliph Al Mamud, was author
of a book entitled "The history of the Patriarchs and Prophets,
_from the Creation of the World_."--Mod. Univ. Hist. vol. ii. ch.
iv.

[39] Translated by MM. Chezy and De Sacy, and cited by M. Elie de
Beaumont, Ann. des Sci. Nat. 1832.

[40] See Venturi's extracts from Da Vinci's MMS. now in Library
of Institute of France. They are not mentioned by Brocchi, and my
attention was first called to them by Mr. Hallam. L. da Vinci
died A. D. 1519.

[41] Museum Calceol.--See Brocchi's Discourse on the Progress of
the Study of Fossil Conchology in Italy, where some of the
following notices on Italian writers will be found more at large.

[42] In Sicily, in particular, the title-deeds of many valuable
grants of land to the monasteries are headed by such preambles,
composed by the testators about the period when the good King
Roger was expelling the Saracens from that island.

[43] De Fossilib. pp. 109, 176.

[44] Aristotle, On Animals, chaps. 1, 15.

[45] Brocchi, Con. Fos. Subap. Disc, sui Progressi. vol. i. p.
57.

[46] De Metallicis.

[47] Dies Caniculares.

[48] Storia Naturale.

[49] Osserv. sugli Animali aquat. e terrest. 1626.

[50] Sex itaque distinctas Etruriae facies agnoscimus, dum bis
fluida, bis plana, et sicca, bis aspera fuerit, &c.

[51] Scilla quotes the remark of Cicero on the story that a stone
in Chios had been cleft open, and presented the head of Paniscus
in relief:--"I believe," said the orator, "that the figure bore
some resemblance to Paniscus, but not such that you would have
deemed it sculptured by Scopas; for chance never perfectly
imitates the truth."

[52] De Testaceis fossilibus Mus. Septaliani.

[53] The opinions of Boyle, alluded to by Quirini, were published
a few years before, in a short article entitled "On the Bottom of
the Sea." From observations collected from the divers of the
pearl fishery, Boyle inferred that, when the waves were six or
seven feet high above the surface of the water, there were no
signs of agitation at the depth of fifteen fathoms; and that even
during heavy gales of wind, the motion of the water was
exceedingly diminished at the depth of twelve or fifteen feet. He
had also learnt from some of his informants, that there were
currents running in opposite directions at different
depths.--Boyle's Works, vol. iii. p. 110. London, 1744.

[54] See Conybeare and Phillips, "Outlines of the Geology of
England and Wales," p. 12.

[55] Unde jam duplex origo intelligitur primorum corporum, una,
cum ab ignis fusione refrigescerent, altera, cum reconcrescerent
ex solutione aquarum.

[56] Redeunte mox simili causa strata subinde alia aliis
imponerentur, et facies teneri adhuc orbis saepius novata est.
Donec quiescentibus causis, atque aequilibratis, consistentior
emergeret rerum status.--For an able analysis of the views of
Leibnitz, in his Protogoea, see Mr. Conybeare's Report to the
Brit. Assoc. on the Progress of Geological Science, 1832.

[57] Between the year 1688 and his death, in 1703, he read
several memoirs to the Royal Society, and delivered lectures on
various subjects, relating to fossil remains and the effects of
earthquakes.

[58] Posth. Works, Lecture, Feb. 29, 1688.

[59] Posth. Works, p. 327.

[60] Posth. Works, Lecture, Feb. 15, 1688. Hooke explained with
considerable clearness the different modes wherein organic
substances may become lapidified; and, among other illustrations,
he mentions some silicified palm-wood brought from Africa, on
which M. de la Hire had read a memoir to the Royal Academy of
France (June, 1692), wherein he had pointed out, not only the
tubes running the length of the trunk, but the roots at one
extremity. De la Hire, says Hooke, also treated of certain trees
found petrified in the "river that passes by Bakan, in the
kingdom of _Ava_, and which has for the space of ten leagues the
virtue of petrifying wood." It is an interesting fact that the
silicified wood of the Irawadi should have attracted attention
more than one hundred years ago. Remarkable discoveries have been
made there in later times of fossil animals and vegetables, by
Mr. Crawfurd and Dr. Wallich.--See Geol. Trans. vol. ii. part
iii. p. 377, second series. De la Hire cites Father Duchatz, in
the second volume of "Observations made in the Indies by the
Jesuits."

[61] Posth. Works, Lecture, May 29, 1689.

[62] Posth. Works, p. 312.

[63] Posth. Works, p. 410.

[64] Ray's Physico-theological Discourses were of somewhat later
date than Hooke's great work on earthquakes. He speaks of Hooke
as one "whom for his learning and deep insight into the mysteries
of nature he deservedly honored."--_On the Deluge_, chap. iv.

[65] Essay towards a Natural History of the Earth, 1695. Preface.

[66] Ibid.

[67] Consequences of the Deluge, p. 165.

[68] First published in Latin between the years 1680 and 1690.

[69] An Examination of Dr. Burnet's Theory, &c., 2d ed. 1734.

[70] Ramazzini even asserted, that the ideas of Burnet were
mainly borrowed from a dialogue of one Patrizio; but Brocchi,
after reading that dialogue, assures us that there was scarcely
any other correspondence between these systems, except that both
were equally whimsical.

[71] Dei Corpi Marini, Lettere critiche, &c. 1721.

[72] Brocchi, p. 28.

[73] Ibid. p. 33.

[74] Ibid.

[75] Sui Crostacei ed altri Corpi Marini che si trovano sui
Monti.

[76] Moro does not cite the works of Hooke and Ray; and although
so many of his views were in accordance with theirs, he was
probably ignorant of their writings, for they had not been
translated. As he always refers to the Latin edition of Burnet,
and a French translation of Woodward, we may presume that he did
not read English.

[77] Saggio fisico intorno alla Storia del Mare, part i. p. 24.

[78] "Abbomino al sommo qualsivoglia sistema, che sia di pianta
fabbricato in aria; massime quando e tale, che non possa
sostenersi senza un miracolo," &c.--De' Crostacei e di altre
Produz. del Mare, &c. 1749.

[79] "Senza violenze, senza finzioni, senza supposti, senza
miracoli." De' Crostacei e di altre Produz. del Mare, &c. 1749.

[80] Sui Testacei della Sicilia.

[81] Hist. Nat. tom. v. ad. de l'Imp. Royale, Paris, 1769.

[82] Essai d'une Hist. Nat. des Couches de la Terre, 1759.

[83] John Gesner published at Leyden, in Latin.

[84] Part ii. chap. 9.

[85] Giornale del Criselini, 1759.

[86] See a sketch of the History of English Geology, by Dr.
Fitton, in Edinb. Rev. Feb. 1818, re-edited Lond. and Edinb.
Phil. Mag. vols. i. and ii. 1832-3. Some of Michell's
observations anticipate in so remarkable a manner the theories
established forty years afterwards, that his writings would
probably have formed an era in the science, if his researches had
been uninterrupted. He held, however, his professorship only
eight years, when his career was suddenly cut short by preferment
to a benefice. From that time he appears to have been engaged in
his clerical duties, and to have entirely discontinued his
scientific pursuits, exemplifying the working of a system still
in force at Oxford and Cambridge, where the chairs of
mathematics, natural philosophy, chemistry, botany, astronomy,
geology, mineralogy, and others, being frequently filled by
clergymen, the reward of success disqualifies them, if they
conscientiously discharge their new duties, from farther
advancing the cause of science, and that, too, at the moment when
their labors would naturally bear the richest fruits.

[87] Sui Corpi Marini del Feltrino, 1761.

[88] De Novis e Mari Natis Insulis. Raspe was also the editor of
the "Philosophical Works of Leibnitz. Amst. et Leipzig, 1765;"
also author of "Tassie's Gems," and "Baron Munchausen's Travels."

[89] Acta Academiae Electoralis Maguntinae, vol. ii. Erfurt.

[90] This account of Fuchsel is derived from an excellent
analysis of his memoirs by M. Keferstein. Journ. de Gaologie,
tom. ii. Oct. 1830.

[91] Saggio orittografico, &c. 1780, and other Works.

[92] Lett. sui Pesci Fossili di Bolca. Milan, 1793.

[93] This argument of Testa has been strengthened of late years
by the discovery that dealers in shells had long been in the
habit of selling Mediterranean species as shells of more southern
and distant latitudes, for the sake of enhancing their price. It
appears, moreover, from several hundred experiments made by that
distinguished hydrographer, Capt. Smith, on the water within
eight fathoms of the surface, that the temperature of the
Mediterranean is on an average 3-1/2 degrees of Fahrenheit higher
than the western part of the Atlantic ocean; an important fact,
which in some degree may help to explain why many species are
common to tropical latitudes and to the Mediterranean.

[94] Inquiry into the Original State and Formation of the Earth,
1778.

[95] Observ. on the Formation of Mountains. Act Petrop. ann.
1778, part i.

[96] Nov. comm. Petr. XVII. Cuvier, Eloge de Pallas.

[97] Cuvier, Eloge de Werner.

[98] I am indebted for this information partly to Messrs.
Sedgwick and Murchison, who have investigated the country, and
partly to Dr. Charles Hartmann, the translator of this work into
German.

[99] Cuvier, Eloge de Desmarest.

[100] Journ. de Phys. vol. xiii. p. 115; and Mam. de l'Inst.,
Sciences Mathamat. et. Phys. vol. vi. p. 219.

[101] Journ. de Phys. tom. xxxv. p. 191.

[102] Ib. tom. xxxvii. part ii. p. 200.

[103] Cuvier, Eloge de Desmarest.

[104] Ed. Phil. Trans. 1788.

[105] Playfair's Works, vol. iv. p. 75.

[106] "Before me things create were none, save things
Eternal."--Dante's _Inferno_, canto iii. Cary's Translation.

[107] Playfair's Works, vol. iv. p. 55.

[108] In allusion to the theories of Burnet, Woodward, and
other physico-theological writers, he declared that they were
as fond of changes of scene on the face of the globe, as were
the populace at a play. "Every one of them destroys and
renovates the earth after his own fashion, as Descartes framed
it: for philosophers put themselves without ceremony in the
place of God, and think to create a universe with a
word."--Dissertation envoyae a l'Academie de Boulogne, sur les
Changemens arrivas dans notre Globe. Unfortunately, this and
similar ridicule directed against the cosmogonists was too well
deserved.

[109] See the chapter on "Des Pierres figuras."

[110] In that essay he lays it down, "that all naturalists are
now agreed that deposits of shells in the midst of the
continents are monuments of the continued occupation of these
districts by the ocean." In another place also, when speaking
of the fossil shells of Touraine, he admits their true origin.

[111] As an instance of his desire to throw doubt
indiscriminately on all geological data, we may recall the
passage where he says, that "the bones of a reindeer and
hippopotamus discovered near Etempes did not prove, as some
would have it, that Lapland and the Nile were once on a tour
from Paris to Orleans, but merely that a lover of curiosities
once preserved them in his cabinet."

[112] "Some drill and bore The solid earth, and from the strata there
Extract a register, by which we learn That he who made it, and
revealed its date To Moses, was mistaken in its age." The Task,
book iii. "The Garden."

[113] P. 577.

[114] P. 59.

[115] Introd. p. 2.

[116] London, 1809.

[117] In a most able article, by Mr. Drinkwater, on the "Life
of Galileo," published in the "Library of Useful Knowledge," it
is stated that both Galileo's work, and the book of Copernicus,
"Nisi corrigatur" (for, with the omission of certain passages,
it was sanctioned), were still to be seen on the forbidden list
of the Index at Rome, in 1828. I was, however, assured in the
same year, by Professor Scarpellini, at Rome, that Pius VII., a
pontiff distinguished for his love of science, had procured a
repeal of the edicts against Galileo and the Copernican system.
He had assembled the Congregation; and the late Cardinal
Toriozzi, assessor of the Sacred Office, proposed that they
should wipe off this scandal from the church." The repeal was
carried, with the dissentient voice of one Dominican only. Long
before that time the Newtonian theory had been taught in the
Sapienza, and all Catholic universities in Europe (with the
exception, I am told, of Salamanca); but it was always required
of professors, in deference to the decrees of the church, to
use the term _hypothesis_, instead of theory. They now speak of
the Copernican _theory_.

[118] Elementary Treatise on Geology. London, 1809. Translated
by De la Fite.

[119] See Dr. Fitton's Memoir, before cited, p. 57.

[120] Whewell, British Critic, No. xvii. p. 187, 1831.

[121] Discours sur les Ravol. &c.

[122] Niebuhr's Hist. of Rome, vol. i. p. 5. Hare and
Thirlwall's translation.

[123] Gibbon, Decline and Fall, chap. xxxiii.

[124] Id. Ibid.

[125] In the earlier editions of this work, a fourth book was
added on Geology Proper, or Systematic Geology, containing an
account of the former changes of the animate and inanimate
creation, brought to light by an examination of the crust of
the earth. This I afterwards (in 1838) expanded into a separate
publication called the Elements of Manual Geology, of which a
fourth edition appeared December, 1851.

[126] See two articles by the Rev. Dr. Fleming, in the
Edinburgh New Phil. Journ. No. xii. p. 277, April, 1829; and
No. xv. p. 65, Jan. 1830.

[127] Book iii. chaps. 46, 47, &c.

[128] Macacus pliocenus, Owen, Brit. Foss. Mam. Intr. p. 37,
found with the extinct elephant, &c. in the modern freshwater
beds at Grays Thurrock (Essex), in the valley of the Thames.

[129] Geol. Proceedings, No. xxxvi. June, 1834.

[130] Phil. Mag., Sept. 1829, and Jan. 1830.

[131] Fleming, Ed. New Phil. Journ., No. xii. p. 282, 1829. The
zebra, however, inhabits chiefly the extra-tropical parts of
Africa.

[132] Humboldt, Fragmens de Gaologie, &c., tome ii. p. 388.
Ehrenberg, Ann. des Sci. Nat., tome xxi. p. 387.

[133] Ehrenberg, ibid. p. 390.

[134] Journ. of Asiat. Soc., vol. i. p. 240.

[135] Rafinesque, Atlantic Journ., p. 18.

[136] Darwin's Journal of Travels in South America, &c., 1832
to 1836, in Voyage of H. M. S. Beagle, p. 159.

[137] Ehrenberg, ibid.

[138] The speculations which follow, on the ancient physical
geography of Siberia, and its former fitness as a residence for
the mammoth, were first given in their present form in my 4th
edition, June, 1835. Recently Sir R. Murchison and his
companions in their great work on the Geology of Russia, 1845
(vol. i. p. 497), have, in citing this chapter, declared that
their investigations have led them to similar conclusions.
Professor Owen, in his excellent History of British Fossil
Mammalia, 1844, p. 261, _et seq._, observes that the teeth of
the mammoth differ from those of the living Asiatic or African
elephant in having a larger proportion of dense enamel, which
may have enabled it to subsist on the coarser ligneous tissues
of trees and shrubs. In short, he is of opinion, that the
structure of its teeth, as well as the nature of its epidermis
and coverings, may have made it "a meet companion for the
reindeer."

[139] Pallas, Reise in Russ. Reiche, pp. 409, 410.

[140] Nov. Com. Petrop. vol. xvii. p. 584.

[141] Nov. Com. Petrop. vol. xvii. p. 591.

[142] Quart. Journ. Geol. Soc. Lond. vol. iv. p. 10, Memoirs.

[143] Journal du Nord, St. Petersburg, 1807.

[144] Fleming, Ed. New Phil. Journ., No. xii. p. 285.
Bishop Heber informs us (Narr. of a Journey through the Upper
Provinces of India, vol. ii. p. 166-219), that in the lower
range of the Himalaya mountains, in the northeastern borders of
the Delhi territory, between lat. 29 degrees and 30 degrees, he
saw an Indian elephant of a small size, covered with shaggy
hair. But this variety must be exceedingly rare; for Mr. Royle
(late superintendent of the East India Company's Botanic Garden
at Saharunpore) has assured me, that being in India when Heber's
Journal appeared, and having never seen or heard of such
elephants, he made the strictest inquiries respecting the fact,
and was never able to obtain any evidence in corroboration. Mr.
Royle resided at Saharunpore, lat. 30 degrees N., upon _the
extreme northern limits_ of the range of the elephant. Mr.
Everest also declares that he has been equally unsuccessful in
finding any one aware of the existence of such a variety or
breed of the animal, though one solitary individual was
mentioned to him as having been seen at Delhi, with a good deal
of long hair upon it. The greatest elevation, says Mr. E., at
which the wild elephant is found in the mountains to the north
of Bengal, is at a place called Nahun, about 4000 feet above the
level of the sea, and in the 31st degree of N. lat., where the
mean yearly temperature may be about 64 degrees Fahrenheit, and
the difference between winter and summer very great, equal to
about 36 degrees F., the month of January averaging 45 degrees,
and June, the hottest month, 81 degrees F. (Everest on climate
of Foss. Eleph., Journ. of Asiat. Soc., No. 25, p. 21.)

[145] See Dr. Buckland's description of these bones, Appen. to
Beechy's Voy.

[146] Darwin, Journal of Travels in S. America, &c., 1832-36,
in voyage of H. M. S. Beagle, p. 98. 2d Ed. London, 1845, p.
86.

[147] Darwin, Journal of Travels in S. America, &c., p. 99, 2d
Ed. p. 85.

[148] Burchell, cited by Darwin, ibid. p. 101. 2d Ed. p. 87.

[149] Since the above passage was first printed in a former
edition, June, 1835, it has been shown by the observations of
Sir R. Murchison, M. de Verneuil, and Count Keyserling, and
more recently by M. Middendorf (see above, p. 81), that the
Lowland of Siberia has actually been extended, since the
existing species of shells inhabited the northern seas.

[150] Humboldt, Fragmens Asiatiques, tom. ii. p. 393.

[151] Reboul. Geol. de la Pariode Quaternaire, who cites
Observ. sur la Sibarie, Bibl. Univ., Juillet, 1832.

[152] Conjectured to be the wild stock of Bos grunniens.

[153] Recollections of a Journey through Tartary, Thibet, and
China (ch. xv. p. 234), by M. Huc. Longman, 1852.

[154] For an account of the more modern changes of the tertiary
fauna and flora of the British Isles and adjoining countries,
and particularly those facts which relate to the "glacial
epoch," see an admirable essay by Prof. E. Forbes. Memoirs of
Geol. Survey of Great Brit. vol. i. p. 336. London, 1846. To
this important memoir I shall have frequent occasion to refer
in the sequel.

[155] See a paper by Charles J. F. Bunbury, Esq., Journ. of
Geol. Soc., London, No. 6, p. 88. 1846.

[156] The Calamites were formerly regarded by Adolphe
Brongniart as belonging to the tribe of Equisetaceae; but he is
now inclined to refer them to the class of gymnogens, or
gymnospermous exogens, which includes the Coniferae and Cycadeae.
Lepidodendron appears to have been either a gigantic form of
the lycopodium tribe, or, as Dr. Lindley thinks, intermediate
between the lycopodia and the fir tribe. The Sigillariae were
formerly supposed by Ad. Brongniart, to be arborescent ferns;
but the discovery of their internal structure, and of their
leaves, has since proved that they have no real affinity to
ferns. According to the view now taken of their structure,
their nearest allies in the recent world are the genera Cycas
and Zamia; while Corda, on the other hand, maintains that they
were closely related to the succulent euphorbias. Stigmaria is
now generally admitted to have been merely the root of
sigillaria. The scalariform vessels of these two genera are not
conclusive in proving them to have a real affinity with ferns,
as Mr. Brown has discovered the same structure of vessels in
Myzodendron, a genus allied to the mistletoe; and Corda has
lately shown that in two species of Stigmaria, hardly
distinguishable by external characters, the vessels of the one
are scalariform, and of the other dotted.

[157] Mr. Lindley endeavored formerly (1834) to show, in the
"Fossil Flora," that Trigonocarpum Noeggerathii, a fruit found
in the coal measures, has the true structure of a palm-fruit;
but Ad. Brongniart has since inclined to regard it as
cycadeous; nor is the French botanist satisfied that some
specimens of supposed palm wood from the coal-mines of Radnitz
in Bohemia, described by Corda, really belong to palms. On the
other hand, Corda has proved Flabellaria borassifolia of
Sternberg to be an exogenous plant, and Brongniart contends
that it was allied to the Cycadeae. See Tableau des Genres de
Vagataux Fossiles. Paris, 1849.

[158] Prodrome d'une Hist. des Vagat. Foss. p. 179. See also a
late paper, Quart. Journ. of Geol. Soc. London, 1846, in which
coal-plants of Alabama, lat. 33 degrees N., collected by the
author, are identified by Mr. Bunbury with British fossil
species, showing the great southern extension of this flora.

[159] Konig, Journ. of Sci., vol. xv. p. 20. Mr. Konig informs
me that he no longer believes any of these fossils to be tree
ferns, as he at first stated, but that they agree generically
with plants in our English coal-beds. The Melville Island
specimens, now in the British Museum, are very obscure
impressions.

[160] Fossil Flora of Great Britain, by John Lindley and
William Hutton, Esqrs., No. IV.

[161] Fossil Flora of Great Britain, by John Lindley and
William Hutton, Esqrs. No. IV.

[162] Fossil Flora, No. X.

[163] This has been proved by Mr. Lindley's experiments, ibid.
No. XVII.

[164] I have treated of this subject in my Manual of Geology,
and still more fully in my Travels in N. America, vol. ii. p.
178. For a full account of the facts at present known, and the
theories entertained by the most eminent geologists and
botanists on this subject, see Mr. Horner's Anniversary Address
to the Geological Society of London, February, 1846. Consult
also Sir H. de la Beche, on the formation of rocks in South
Wales, Memoirs of Geol. Survey of Great Britain, 1846, p. 1 to
296.

[165] The theory proposed in this and the following chapters,
to account for former fluctuations of climate at successive
geological periods, agrees in every essential particular, and
has indeed been reprinted almost verbatim from that published
by me twenty years ago in the first edition of my Principles,
1830. It was referred to by Sir John F. W. Herschel in his
Discourse on Natural Philosophy, published in 1830. In
preceding works the gradual diminution of the earth's central
heat was almost the only cause assigned for the acknowledged
diminution of the superficial temperature of our planet.

[166] We are indebted to Baron Alex. von Humboldt for having
first collected together the scattered data on which he founded
an approximation to a true theory of the distribution of heat
over the globe. Many of these data were derived from the
author's own observations, and many from the works of M. Pierre
Prevost, of Genera, on the radiation of heat, and from other
writers.--See Humboldt on Isothermal Lines, Mamoires d'Arcueil,
tom. iii. translated in the Edin. Phil. Journ. vol. iii. July,
1820.

The map of Isothermal Lines, recently published by Humboldt and
Dove (1848), supplies a large body of well-established data for
such investigations, of which Mr. Hopkins has most ably availed
himself in an essay "On the Causes which may have produced
Changes in the earth's Superficial Temperature."--Q. Journ.
Geol. Soc. 1852, p. 56.

[167] Sir J. Richardson's Appendix to Sir G. Bach's Journal,
1843-1845, p. 478.

[168] Malte-Brun, Phys. Geol. book xvii.

[169] On Isothermal Lines, &c.

[170] Rennell on Currents, p. 96. London, 1832.

[171] Ibid. p. 153.

[172] Ibid. p. 25.

[173] Scoresby's Arctic Regions, vol. i. p. 208.--Dr. Latta's
Observations on the Glaciers of Spitzbergen, &c. Edin. New
Phil. Journ. vol. iii. p. 97.

[174] Rennell on Currents, p. 95.

[175] Humboldt on Isothermal Lines.

[176] Journ. of Travels in S. America, &c. p. 272.

[177] Darwin's travels in S. America, p. 271.

[178] Mr. Hopkins raises the question whether, in South
Georgia, the descent of glaciers to the margin of the sea might
not have been mistaken by Capt. Cook for the descent of the
snow-line to the sea level. Quart. Journ. Geol. Soc. p. 85,
1852. The great navigator is generally very accurate, and there
seem to be no observations of more recent date either to
confirm or invalidate his statements.

[179] After all these modern discoveries, the area still
unexplored, within the antarctic circle, is more than double
the area of Europe. The surface of the latter contains about
2,793,000 square geographical miles. The unexplored antarctic
region, as calculated for me by Mr. Gardner, in 1840, equalled
about 7,620,000 square miles.

[180] On icebergs in low latitudes, by Capt. Horsburgh, by whom
the sketch was made. Phil. Trans. 1830.

[181] Scoresby's Arctic Regions, vol. i. p. 234.

[182] This follows, observes Herschel, from a very simple
theorem, which may be thus stated:--"The amount of heat
received by the earth from the sun, while describing any part
of its orbit, is proportional to the angle described round the
sun's centre." So that if the orbit be divided into two
portions by a line drawn _in any direction_ through the sun's
centre, the heat received in describing the two unequal
segments of the eclipse so produced will be equal. Geol. Trans.
vol. iii. part. ii. p. 298; second series.

[183] On Isothermal Lines.

[184] A full consideration of the effect of changes in physical
geography on the distribution and extinction of species is
given in book iii.

[185] For calculations founded on astronomical data, see
Young's Nat. Phil., Lect. xlvii.; Mrs. Somerville's Connex. of
Phys. Sci., sect. 14, p. 110. Laplace, endeavoring to estimate
the probable depth of the sea from some of the phenomena of the
tides, says of the ocean generally, "que sa profondeur moyenne
est du meme ordre que la hauteur moyenne des continens et des
isles au-dessus de son niveau, hauteur qui ne surpasse pas
mille metres (3280 ft.)" Mec. Caleste, tom. xi. et Syst. du
Monde, p. 254. The expression "du meme ordre" admits in
mathematical language of considerable latitude of
signification, and does not mean that the depth of the water
below the level of the sea corresponds exactly to the height of
the land above it.

It appeared from the observations of Sir James Ross,
communicated to me in 1849, by himself, and his fellow voyager,
Dr. Joseph Hooker, that in latitude 15 degrees 3 minutes S.,
longitude 23 degrees 14 minutes W. (the island of Trinidad, the
nearest land, being 486 miles distant, and bearing S. 47 W.),
they sounded with a weight of 76 lbs., and 4600 fathoms of line,
which ran out to the very end, without finding bottom. Here
therefore in mid-ocean the depth exceeded 27,600 feet. One of
the shallowest soundings ever obtained in the open sea during
the same survey, struck bottom with 2677 fathoms, or 16,062
feet, latitude 33 degrees 21 minutes S., longitude 9 degrees 4
minutes E. The surveyors arrived at the conclusion, that at a
moderate distance from the shore, the depth of the great ocean
always exceeds 4000 feet.

During the American survey in 1849, a much greater depth, or
5700 fathoms (34,200 feet), was sounded in the Atlantic by
Lieut. Walsh, without reaching the bottom, in lat. 31 degrees 59
minutes N., long. 58 degrees 43 minutes W., or between the
Bermudas and the Azores. But the deepest soundings yet published
were taken Oct. 30th 1852, by Capt. Henry M. Denham, R. N., who
reached bottom at 7706 fathoms (46,236 feet), lat. 36 degrees 49
minutes S., long. 37 degrees 6 minutes W., the nearest land
being at the mouth of the River Plate. A weight of 9 lbs. was
attached to the line, which was one-tenth of an inch in
diameter; the day was calm, and the line took 9 hours 24 minutes
to run out. When the bottom was struck the line was raised 50
fathoms, and then allowed to run out again. It struck at the
same point as before, verifying the observations. Nevertheless
some experienced surveyors have remarked that the experiment
would have been more satisfactory had the weight been greater.
The highest summits of the Himalaya are about 28,000 feet; the
Pacific, according to this sounding, is probably at some points
twice as deep as the Himalaya are high.

[186] Mr. Hopkins, reasoning on data furnished by Dove's
Isothermal maps, has arrived at the very interesting
conclusion, that both on Snowdon and the lower mountains of the
West of Ireland the snow-line would descend to within 1000 feet
of the sea level, and glaciers reach the sea, if we could
simply assume the three following geographical changes:--

1st, The diversion of the Gulf stream from its present
northerly course; 2dly, the depression of the existing land of
Northern and Western Europe, to the amount of no more than 500
feet; and 3dly, a cold current from the North sweeping over the
submerged area. Quart. Journ. Geol. Soc. 1852, p. 85.

[187] Daniell's Meteorological Essays, p. 103.

[188] Observed by J. Crawfurd, Esq.

[189] In speaking of the circulation of air and water in this
chapter, no allusion is made to the trade winds, or to
irregularities in the direction of currents, caused by the
rotary motion of the earth. These causes prevent the movements
from being direct from north to south, or from south to north,
but they do not affect the theory of a constant circulation.

[190] See Scoreby's Arctic Regions, vol. i. p. 378.

[191] Ibid. p. 320.

[192] This is shown by projecting a map on the horizon of
London, that is to say, by supposing the eye of the observer to
be placed above that city, and to see from thence one half of
the globe. For it so happens that from that point, and no
other, we should behold the greatest possible quantity of land;
and if we are then transferred to the opposite or antipodal
point, we should see the greatest possible quantity of water.
(See figs. 3 and 4.) A singular fact, first pointed out by Mr.
James Gardner, namely, that only one twenty-seventh part of the
dry land has any land opposite to it, is intimately connected
with this excess of land in one of the two hemispheres above
alluded to. Thus, in fig. 3, the land shaded black in part of
China answers to that portion of the extremity of South America
and Tierra del Fuego which is opposite or antipodal to it,
whilst the dark spots in the northern and central parts of
South America represent Borneo, Sumatra, and other antipodal
islands in the Eastern Archipelago. See Gardner, Geol. Soc.
Proceedings, 1833, vol. i. p. 488.

[193] Humboldt on Isothermal Lines

[194] Humboldt, Tableaux de la Nature, tom. i. p. 112.

[195] Ad. Brongniart, Consid. Ganarales sur la Nat. de la
Vagat. &c. Ann. des Sciences Nat., Nov. 1828.

[196] Sir J. Richardson, Proceedings of Geol. Soc. No. 7, p.
68, March, 1828.

[197] Ad. Brongniart, Consid. Ganarales sur la Nat. de la
Vagat. &c., Ann. des Sci. Nat., Nov. 1828.

[198] See a Memoir on the Alps, by Professor Sedgwick and Sir
Rod. Murchison, Trans. of Geol. Soc. second ser. vol. iii.
accompanied by a map.

[199] See Proceedings of Geol. Soc. vol. ii. p. 334.