Cosmos: A Sketch of the Physical Description of the Universe Part 32

[footnote[ *Adolphe Brongniart, 'Prodrome d'une Hist. des Vegetaux Fossiles', p. 179; buckland, 'Geology', p. 479; Endlicher and Unger, 'Grundzuge der Botanik', 1843, s. 455.

The vegetation of the primitive period exhibits forms which, from their simultaneous affinity with several families of the present world, testify that many intermediate links must have become extinct in the scale of organic development. Thus, for example, to mention only two instances, we would notice the Lepidodendra, which, according to Lindley, occupy a place between the Coniferae and the Lycopodiaceae*, and the Araucariae and pines, which exhibit some peculiarities in the union of their vascular bundles.

[footnote] *"By means of Lepidodendron, a better pa.s.sage is established from flowering to flowerless plants than by either Equisetum or Cycas, or any other known genus." -- Lindley and Hutton, 'Fossil Flora', vol. ii., p.

53.

Even if we limit our consideration to the present world alone, we must regard as highly important the discovery of Cycadeae and Coniferae side by side with Sagenariae and Lepidodendra in the ancient coal measures. The Coniferae are not ony allied to Cupuliferae and Betulinae, with which we find them a.s.sociated in lignite formations, but also with Lycopodiaceae.

The family of the sago-like Cycadeae approaches most nearly to palms in its external appearance, while these plants are specially allied to Coniferae in respect to the structure of their blossoms and seed.*

[footnote] *Kunth, 'Anordnung der Pflanzenfamilien', in his 'Handb. der Botanik', s. 307 und 314.

Where many beds of coal are superposed over one another, the families and species are not always blended, being most frequently grouped together in separate genera; Lycopodiaceae and certain ferns being alone found in one bed, and Stigmariae and Sigillariae in another. In order to give some idea of the luxuriance of the vegetation of the primitive world, and of the immense ma.s.ses of vegetable matter which was doubtlessly acc.u.mulated in currents and converted in a moist condition into coal,* I would instance the Saarbrucker coal measures, p 281 where 120 beds are superposed on one another, exclusive of a great many which are less than a foot in thickness; the coal beds at Johnstone, in Scotland, and those in the Creuzot, in Burgundy, are some of them, respectively, thirty and fifty feet in thickness,** while in the forests of our temperate zones, the carbon contained in the trees growing over a certain area would hardly suffice, in the s.p.a.ce of a hundred years, to cover it with more than a stratum of seven French lines in thickness.***

[footnote] That coal has not been formed from vegetable fibers charred by fire, but that it has more probably been produced in the moist way by the action of sulphuric acid, is strikingly demonstrated by the excellent observation made by Goppert (Karsten, 'Archiv fu Mineralogie', bd. xviii., s. 530), on the conversion of a fragment of amber-tree into black coal. The coal and the unaltered amber lay side by side. Regarding the part which the lower forms of vegetation may have had in the formation of coal beds, see Link, in the 'Abhandl. der Berliner Akademie der Wissenschaften', 1838, s.

38.

[footnote] **[The actual total thickness of the different beds in England varies considerably in different districts, but appears to amount in the Lancas.h.i.+re coal field to as much as 150 feet. -- Ansted's 'Ancient World', p. 78. For an enumeration of the thickness of coal measures in America and the Old Continent, see Mantell's 'Wonders of Geology', vol. ii., p. 60.] -- Tr.

[footnote] ***See the accurate labors of Chevandier, in the 'Comptes Rendus de l'Academie des Sciences', 1844, t. xviii., Part i., p. 285. In comparing this bed of carbon, seven lines in thickness, with beds of coal, we must not omit to consider the enormous pressure to which the latter have been subjected from superimposed rock, and which manifests itself in the flattened form of the stems of the trees found in these subterranean regions. "The so-called 'wood-hills' discovered in 1806 by Sirowatskoi, on the south coast of the island of New Siberia, consist, according to Hedenstrom, of horizontal strata of sandstone, aolternating with bituminous trunks of trees, forming a mound thirty fathoms in neight; at the summit the stems were in a vertical position. The bed of driftwood is visible at five wersts' distance." -- See Wrangel, 'Reise Iangs der Nordkuste von Siberien, in den Jahren' 1820-24, th. i., s. 102.

Near the mouth of the Mississippi, and in the "wood hills" of the Siberian Polar Sea, described by Admiral Wrangel, the vast number of trunks of trees acc.u.mulated by river and sea water currents affords a striking instance of theenormous quant.i.ties of drift-wood which must have favored the formation of carboniferous deposition in the island waters and insular bays. There can be no doubt that these beds owe a considerable portion of the substances of which they consist to gra.s.ses, small branching shrubs, and cryptogamic plants.

The a.s.sociation of palms and Coniferae, which we have indicated as being characteristic of the coal formations, is discoverable throughout almost all formations to the tertiary period. In the present condition of the world, these genera p 282 appear to exhibit no tendency whatever to occur a.s.sociated together. We have so accustomed ourselves, although erroneously, to regard Coniferae as a northern form, that I experienced a feeling of surprise when, in ascending from the sh.o.r.es of the South Pacific toward Chilpansingo and the elevated valleys of Mexico, between the 'Venta de la Moxonera' and the 'Alto de los Caxones', 4000 feet above the level of the sea, I rode a whole day through a dense wood of Pinus occidentalis, where I observed that these trees, which are so similar to the Weymouth pine, were a.s.sociated with fan palms*

('Corypha dulcis'), swarming with brightly-colored parrots.

[[footnote] *This corypha is the 'soyate' (in Aztec, zoyatl), or the 'Palma dulce' of the natives. See Humboldt and Bonplaud, 'Synopsis Plant.

AEquinoct. Orbis Novi', t. i., p. 302. Professor Buschmann, who is profoundly acquainted with the American languages, remarks, that the 'Palma soyate' is so named in Yepe's 'Vocabulario de la Lengua Othomi', and that the Aztec word zoyatl (Molina, 'Vocabulario en Lengua Mexicana y Castellana', p. 25) recurs in names of places, such as Zoyat.i.tlan and Zoyapanco, near Chiapa.

South America has oaks, but not a single species of pine; and the first time that I again saw the familiar form of a fir-tree, it was thus a.s.sociated with the strange appearance of the fan palm.*

[footnote] *Near Baracoa and Cayos de Moya. See the Admiral's journal of the 25th and 27th of November, 1492, and Humboldt, 'Examen Critique de l'Hist. de la Geographie du Nouveau Continent', t. ii., p. 252, and 5. iii., p. 23. Columbus, who invariably paid the most remarkable attention to all natural objects, was the first to observe the difference between 'Podocarpus' and 'Pinus'. "I find," said he, "en la tierra aspera del Cibao pinos que no Ilevan pinas (fir cones), pero portal orden compuestos por naturaleza, que (los frutos) parecen azeytunas del Axarafe de Sevilla." The great botanist, Richard, when he published his excellent Memoir on Cycadeae and Coniferae, little imagined that before the time of L'Heritier, and even before the end of the fifteenth century, a navigator had separated 'Podocarpus' from the Abietineae.

Christopher Columbus, in his first voyage of discovery, saw Coniferae and palms growing together on the northeastern extremity of the island of Cuba, likewise within the tropics, and scarcely above the level of the sea. This acute observer, whom nothing escaped, mentions the fact in his journal as a remarkable circ.u.mstance, and his friend Anghiera, the secretary of Frdinand the Catholic, remarks with astonishment "that 'palmeta' and 'pineta' are found a.s.sociated together in the newly-discovered land." It is a matter of much importance to geology to compare the present distribution of plants over the earth's surface with that exhibited in the fossil floras of the primitive world. The temperate zone of the southern hemisphere, which is so rich in seas and islands, and where p 283 tropical forms blend so remarkably with those of colder parts of the earth, presents according to Darwin's beautiful and animated descriptions,* the most instructive materials for the study of the present and the past geography of plants.

[footnote] *Charles Darwin, 'Journal of the Voyages of the Adventure and Beagle', 1839, p. 271.

The history of the primordial ages is, in the strict sense of the word, a part of the history of plants.

Cycadeae, which, from the number of their fossil species, must have occupied a far more important part in the extinct than in the present vegetable world, are a.s.sociated with the nearly allied Coniferae from the coal formations upward. They are almost wholly absent in the epoch of the variegated sandstone which contains Coniferae of rare and luxuriant structure ('Voltizia, Haidingera, Albertia'); the Cycadeae, however, occur most frequently in the keuper and lias strata, in which more than twenty different forms appear. In the chalk, marine plants and naiades predominate. The forests of Cycadeae of the Jura formations had, therefore, long disappeared, and even in the more ancient tertiary formations they are quite subordinate to the Coniferae and palms.*

[footnote] *Goppert describes three other Cycadeae (species of Cycadites and Pterophyllum), found in the brown carboniferous schistose clay of Alt-sattel and Commotau, in Bohemia. They very probably belong to the Eocene Period. Goppert, 'Fossile Cycadeen', s. 61.

The lignites, or beds of brown coal* which are present in all divisions of the tertiary period, present, among the most ancient cryptogamic land plants, some few palms, many Coniferae having distinct annual rings, and foliaceous shrubs of a more or less tropical character.

[footnote] *['Medals of Creation', vol. i., ch. v., etc. 'Wonders of Geology', vol. i., p. 278, 392.] -- Tr.

In the middle tertiary period we again find palms and Cycadeae fully established, and finally a great similarity with our existing flora, manifested in the sudden and abundant occurrence of our pines and firs, Cupuliferae, maples, and poplars. The dicotyledonous stems found in lignite are occasionally distinguished by colossal size and great age. In the trunk of a tree found at Bonn, Noggerath counted 792 annual rings.*

[footnote] *Buckland, 'Geology', p. 509.

In the north of France, at Yseux, near Abbeville, oaks have been discovered in the turf moors of the Somme which measured fourteen feet in diameter, a thickness which is very remarkable in the Old Continent and without the tropics. According to Goppert's excellent investigations, which, it is hoped, may soon be ill.u.s.trated by plates, it would appear that "all the amber of the Baltic comes from p 284 a coniferous tree, which, to judge by the still extant remains of wood and the bark at different ages, approaches very nearly to our white and red pines, although forming a distinct species. The amber-tree of the ancient world ('Pinites succifer') abounded in resin to a degree far surpa.s.sing that manifested by any extant coniferous tree; for not only were large ma.s.ses of amber deposited in and upon the bark, but also in the wood itself, following the course of the medullary rays, which, together with ligneous cells, are still discernible under the microscope, and peripherally between the rings, being some times both yellow and white."

"Among the vegetable forms inclosed in amber are male and femald blossoms of our native needle-wood trees and Cupuliferae, while fragments which are recognized as belonging to thuia, cupressus, ephedera, and castania vesca, blended with those of junipers and firs, indicate a vegetation different from that of the coasts and plains of the Baltic."*

[footnote] *{The forests of amber-pines, 'Pinites succifer', were in the southeastern part of what is now the bed of the Baltic, in about 55 degrees N. lat., and 37 degrees E. long. The different colors of amber are derived from local chemical admixture. The amber contains fragments of vegetable matter, and from these it has been ascertained tht the amber-pine forests contained four other species of pine (besides the 'Pinites succier'), several cypresses, yews, and junipers, with oaks, poplars, beeches, etc. -- altogether forty-eight species of trees and shrubs, const.i.tuting a flora of North American chracter. There are also some ferns, mosses, fungi, and liverworts. See Professor Goppert, 'Geol. Trans.', 1845. Insects, spiders, small crustaceans, leaves, and fragments of vegetable tissue, are imbedded in some of the ma.s.ses. Upward of 800 species of insects have been observed; most of them belong to species, and even genera, that appear to be distinct from any now known, but others are nearly related to indigenous species, and some are identical with existing forms, that inhabit more southern climes.

-- 'Wonders of Geology', vol. i., p. 242, etc.] -- Tr.

We have now pa.s.sed through the whole series of formations comprised in the geological portion of the present work, proceeding from the oldest erupted rock and the most ancient sedimentary formations to the alluvial land on which are scattered those large ma.s.ses of rock, the causes of whose general distribution have been so long and variously discussed, and which are, in my opinion, to be ascribed rather to the penetration and violent outpouring of pent-up waters by the elevation of mountain chains than to the motion of floating blocks of ice.*

[footnote] *Leopold von Buch, in the 'Abhandl. der Akad. der Wissensch. zu Berlin', 1814-15, s. 161; and in Poggend., 'Annalen', bd. ix., s. 575; Elie de Beaumont, in the 'Annales des Sciences Naturelles', t. xix., p. 60.

The most ancient structures of the transition formation p 285 with which we are acquainted are slate and graywacke, which contain some remains of sea weeds from the silurian or cambrian sea. On what did these so-called 'most ancient' formations rest, if gneiss and mica schist must be regarded as changed sedimentary strata? Dare we hazard a conjecture on that which can not be an object of actual geognostic observation? According to an ancient Indian myth, the earth is borne up by an elephant, who in his turn is supported by a gigantic tortoise, in order that he may not fall; but it is not permitted to the credulous Brahmins to inquire on what the tortoise rests. We venture here upon a somewhat similar problem, and are prepared to meet with opposition in our endeavors to arrive at its soluion.

In the first formation of the planets, as we stated in the astronomical portion of this work, it is probable that nebulous rings revolving round the sun were agglomerated into spheroids, and consolidated by a gradual condensation proceeding from the exterior toward the center. What we term the ancient silurian strata are thus only the upper portions of the solid crust of the earth. The erupted rocks which have broken through and upheaved these strata have been elevated from depths that are wholly inaccessible to our research; they must, therefore, have existed under the silurian strata, and been composed of the same a.s.sociation of minerals which we term granite, augite, and quartzose porphyry, when they are made known to us by eruption through the surface. Basing our inquiries on a.n.a.logy, we may a.s.sume that the substances which fill up deep fissures and traverse the sedimentary strata are merely the ramifications of a lower deposit. The foci of active volcanoes are situated at enormous depths, and judging from the remarkable fragments which I have found in various parts of the earth incrusted in lava currents, I should deem it more than probable tht a primordial granite rock forms the substratum of the whole stratified edifice of fossil remains.*

[footnote] *See Elie de Beaumont, 'Descr. Geol. de la France', t. i., p.

65; Beaudant, 'Geologie', 1844, p. 269.

Basalt containing olivine first shows itself in the period of the chalk trachyte still later, while eruptions of granite belong, as we learn from the products of their metamorphic action to the epoch of the oldest sedimentary strata of the transition formation. Where knowledge can not be attained from immediate perceptive evidence, we may be allowed from induction, no less than from a careful comparison of facts, to hazard a conjecture by which granite would be restored p 286 to a portion of its contested right and t.i.tle to be considered as a 'primordial' rock.

The recent progress of geognosy, that is to say, the more extended knowledge of the geognostic epochs characterized by differences of mineral formations, by the peculiarities and succession of the organisms contained within them, and by the position of the strata, whether uplifted or inclined horizontally, leads us, by means of the causal connection existing among all natural phenomena, to the distribution of solids and fluids into the continents and seas which const.i.tute the upper crust of our planet. We here touch upon a point of contact between geological and geographical geognosy which would const.i.tute the complete history of the form and extent of continents. The limitation of the solid by the fluid parts of the earth's surface and their mutual relations of area, have varied very considerably in the long series of geognostic epochs. They were very different, for instance, when carboniferous strata were horizontally deposited on the inclined beds of the mountain limestone and old red sandstone; when lias and oolite lay on a substratum of keuper and muschelkalk, and the chalk rested on the slopes of green sandstone and Jura limestone. If, with Elie de Beaumont, we term the waters in which the Jura limestone and chalk formed a soft deposit the 'Jura.s.sic or oolitic', and the 'cretaceous seas', the outlines of these formations will indicate, for the two corresponding epochs, the boundaries between the already dried land and the ocean in which these rocks were forming. An ingenious attempt has been made to craw maps of this physical portion of primitive geography and we may consider such diagrams as more correct than those of the wanderings of Io or the Homeric geography, since the latter are merely graphic representations of mythical images, while the former are based upon positive facts deduced from the science of geology.