Part 11

"1_st_, The great quantity of Algæ and marine Naiades, characters owing to the extent and thickness of the marine formations of this epoch.

"2_d_, The great number of Coniferæ, the greater part belonging to genera still existing, but among which the Cupressineæ appear to predominate, especially if we admit as positively belonging to this family the various fruits of the Isle of Sheppey, which M. Bowerbank has described under the name of Cupressinites, and of which M. Endlicher has formed the genera Callitrites, Frenelites, and Solenostrobus. If these fruits really belong to European vegetation, they indicate very peculiar generic forms, probably now wholly extinct.

"3_d_, The existence of many large species of palm, equally shewn by the occurrence of their leaves and stems.

"2. _Miocene Epoch._--This Eocene or middle epoch of the Tertiary formations appears to me to comprehend the following localities among those which have furnished materials for the study of the vegetation of the Tertiary period: 1_st_, In the environs of Paris, the superior sandstones, or those of Fontainebleau and the _Meulieres_, or Buhrstone, which crown our coasts; 2_d_, The sandstone, with impressions, in the environs of Mans and Angers, and probably those of Bergerac, in the department of the Dordogne; 3_d_, A part of the Tertiary formations of Auvergne, and particularly those of the mountain Gergovia, formations which, by their impressions, appear more ancient than those of Menat, but which perhaps all belong to different stages of the Pliocene epoch; 4_th_, The fresh-water formations of Armissan, near Narbonne, the Gypsum of Aix in Provence, the Lignites of Provence, whose vegetable fossils are scarcely known; finally, the Lacustrine formations, rich in the wood of palms, and in stems of Monocotyledons, from Upper Provence, near Apt and Castellane; 5_th_, A part of the Tertiary formations of Italy, and particularly those of Superga, near Turin; 6_th_, The Mollasse of Switzerland, with its Lignites, at Lausanne, Koepfnac, and Horgen, containing the remains of palms; 7_th_, The Lignites of the banks of the Rhine near Cologne and Bonn, at Friesborf, Liblar, &c., sometimes enclosing wood of palms, and those of Wetteravia at Nidda, near Frankfort, and other places; as well as those of Weisner near Cassel, which all appear to be of the same epoch, although those of Wetteravia, by the abundance of certain genera of Dicotyledons, such as _juglans_ and _acer_, and even by many cases of specific identity, seem to make a nearer approach to the Pliocene flora; 8_th_, A part of the Lignites of Bohemia, and particularly those of Altsattel, whose fossils, described by M. de Sternberg and M. Rossmæssler, generally agree with those of the other localities already mentioned. The other Lignites of Bohemia, those of Bilin and of Comothau in particular, enter completely into the Pliocene flora; 9_th_, Hoerring in the Tyrol, and Radoboj in Croatia, of which M. Unger has so well described the numerous impressions in his _Chloris Protogæa_, and which have almost become the type of the Miocene flora.

"With the exception of the Lignite formations of the neighbourhood of Cassel and Frankfort--the species of which have often numerous points of connection with those of OEningen and Parschlug, and which enter rather into the Pliocene flora--the different localities I have mentioned have numerous relations between them as to their fossil vegetables. Thus, the Nymphea Arethusæ is found in the _Meulières_ or Buhrstone of Paris, and in the marls of Armissan; the Flabellaria rhapifolia and maxima recur at Hoering in the Tyrol, at Radoboj in Croatia, and in the superior sandstones of the environs of Angers and Perigneux.

"The Callitrites Brongniartii, Endl., is likewise met with in the formations of Armissan, Aix, in Provence, at Hoering and Radoboj.

"Lastly, the Steinhauera globosa of the Altsattel Lignites in Bohemia, is likewise found in the sandstone of the vicinity of Maus; and the Platanus Hercules of Radoboj, in Croatia, has been sent to me from Armissan, near Narbonne, by M. Toumal.

"These facts would probably multiply by a more attentive study of the different localities; but as it is, they leave little doubt as to the synchronism of the greater part of these local formations."

In the Flora of the Miocene formations, Amphigenous cryptogams occur, represented by Algæ and mushrooms; Acrogenous cryptogams, represented by mosses, ferns, and Characeæ; Monocotyledons, among which we find Naiades, Gramineæ, Liliaceæ, and Palms; of the Gymnospermous dicotyledons, Coniferæ; and Angiospermous dicotyledons, among which occur Myriceæ, Betulineæ, Cupuliferæ, Ulmaceæ, Moreæ, Plataneæ, Salicineæ, Lawrineæ, Umbelliferæ, Karolangeæ, Combretaceæ, Calycantheæ, Leguminosæ, Anacardiæ, Xanthoxyleæ, Juglandeæ, Rhamneæ, Acerineæ, Nympheaceæ, Apocyneæ, and Rubiaceæ.

"The most striking characters of this epoch consist of the mixture of exotic forms at present peculiar to regions warmer than Europe, with vegetables growing generally in temperate countries; such as the palms, a species of bamboo, Lawrineæ, Combretaceæ, Leguminosæ of warm countries, Apocyneæ, analogous, according to M. Unger, to the genera of equatorial regions, a Rubiaceæ altogether tropical, united with _erables_, walnuts, birches, elms, oaks, _charmes_, &c., genera proper to temperate or cold regions. The presence of equatorial forms, and particularly of palms, appears to distinguish this epoch essentially from the following one. Lastly, we likewise observe the very small number of vegetables with a monopetalous corolla, limited to species referred to the family of Apocyneæ by Unger, and to the genus Steinhauera, founded on a fruit which has much relation to that of Nauclea among the Rubiaceæ.

"3. _Pliocene Epoch._--This epoch, embracing all the Tertiary formations superior to the _fahluns_ of Touraine, comprehends pretty numerous localities rich in fossil vegetables, and whose position in these formations is determined as much by the _ensemble_ of the vegetables they contain, as by their other geological characters. The Tertiary basins which, it appears to me, must serve as the basis of this Flora, both by their identity, and the numerous and carefully-studied vegetables they contain, are: 1st, That of OEningen, near Shaffouse, the species of which have been long since studied and well determined by M. Alex. Braun, whose work, though unpublished, has been communicated to many naturalists, and particularly to M. Unger.[44] 2_d_, That of Parschlug, in Styria, the numerous impressions of which M. Unger has collected, studied, and determined, partly published by him in his _Chloris Protogæa_, and presented altogether in a special enumeration of these species recently published under the title of _Flora of Parschlug_. In this locality alone, M. Unger has recognised and classified 140 different species; it is the most numerous local Flora with which we are acquainted, and the identity of a great number of species with those of OEningen, indicates well the synchronism of these two local formations. Such other points in Styria appear likewise to be of the same epoch, as well as many localities in Hungary so rich in silicified wood. In Bohemia, the tripoli slates of Bilin and Comothau, which contain a pretty considerable number of plants described by M. de Sternberg, are no doubt referrible to this epoch, according to the nature of these plants. Lastly, the Tertiary hills, called the sub-appennine hills of Plaisantin, of Tuscany, and a part of Piedmont, as well as the gypseous formation of Stradella, near Pavia, so rich in impressions of leaves, form part of this epoch; but, with the exception of this latter point, these formations contain, in general, few vegetables.

Footnote 44: The following interesting observations on the OEningen formation are by Professor Agassiz, who refers it to the Miocene not to the Pliocene class:--

"This picture would be incomplete did I not institute a farther comparison between the present vegetation of those regions and the fossil plants of modern geological epochs. If we compare, namely, the Tertiary fossil plants of Europe with those living on the spot now, we shall be struck with the differences of about the same value as those already mentioned between the eastern and western coasts of the continents under the same latitudes. Compare, for instance, a list of the fossil trees and shrubs from OEningen, with a catalogue of trees and shrubs of the eastern and western coasts, both of Europe, Asia, and North America, and it will be seen that the differences they exhibit scarcely go beyond those shewn by these different Floræ under the same latitudes. But what is quite extraordinary and unexpected is the fact, that the European fossil plants of that locality resemble more closely the trees and shrubs which grow at present in the eastern parts of North America, than those of any other part of the world; thus, allowing us to express correctly the differences already mentioned between the vegetation of the eastern and western coasts of the continents, by saying that the present eastern American flora, and I may add, the fauna also,[A] and probably also that of eastern Asia, have a _more ancient character_ than those of Europe and of western North America. The plants, especially the trees and shrubs growing in our days in this country and in Japan, are, as it were, old fashioned; they bear the mark of former ages--a peculiarity which agrees with the general aspect of North America; the geological structure of which indicates that this region was a large continent long before the extensive tracts of land had been lifted above the level of the sea in any other part of the world.

"The extraordinary analogy which exists between the present Flora and Fauna of North America, and the fossils of the Miocene period in Europe, would also give a valuable hint with respect to the mean annual temperature of that geological period.

"_OEningen_, for instance, whose fossils of all classes have perhaps been more fully studied than those of any other locality, could not have enjoyed, during that period, a tropical or even a subtropical climate, such as has often been assigned to it, if we can at all rely upon the indications of its Flora; for this is so similar to that of Charleston, South Carolina, that the highest mean annual temperature we can ascribe to the Miocene epoch in central Europe must be reduced to about 60° Fah.; that is to say, we infer from its fossil vegetation that OEningen had, during the Tertiary times, the climate of the warm temperate zone, the climate of Rome, for instance, and not even that of the northern shores of Africa. We are led to this conclusion by the following argument:--The same isothermal line which passes at present through OEningen, at the 47th degree of northern latitude, passes also through Boston, lat. 42°. Supposing now (as the geological structure of the two continents and the form of their respective outlines at that period seem to indicate), that the undulations of the isothermal lines which we notice in our days existed already during the Tertiary period, or, in other words, that the differences of temperature which exist between the western shores of Europe and the eastern shores of North America, were the same at that time as now, we shall obtain the mean annual temperature of that age by adding simply the difference of mean annual temperature which exists between Charleston and Boston (12° Fah.) to that of OEningen, which is 48° Fah., as modern OEningen agrees almost precisely with Boston, making it 60° Fah.; far from looking to the northern shores of Africa for an analogy, which the different character of the respective vegetations would render still less striking. The mean annual temperature of OEningen, during the Tertiary period, would not therefore differ more from its present mean than that of Charleston differs from that of Boston."--_Agassiz_, _on Lake Superior_, p. 150.

Footnote A: The characteristic genera Lagomys, Cheldyra, and the large Salamanders with permanent gills, remind us of the fossils of OEningen, for the present fauna of Japan, as well as the Liquidambar, Carya, Taxodium, Gleditschia, &c., &c.

"In France, the Pliocene epoch probably comprehends a part of the fresh-water deposits of Auvergne and Ardêche. Thus, the slates of Menat and those of Rochesauve appear to me to furnish a Flora very similar to those of OEningen and Parschlug. With regard to the marls of Gergovia and Merdogne, near Clermont, I think they ought rather to be classed in the Miocene epoch; but this question can be settled only by a more attentive determination of the species. The Flora, which recapitulates all that has been described or named in these formations, is, however, essentially founded, as may be seen by the indication of localities, on the two basins of Parschlug and OEningen.

"The Flora of the Pliocene formations is constituted by Amphigenous cryptogams, comprehending algæ and mushrooms; by Acrogenous cryptogams, including a muscite, ferns, lycopodiaceæ, and equisitaceæ; by Monocotyledons, naiades, gramineæ, cyperaceæ, and liliaceæ; by Gymnospermous dicotyledons, coniferæ, represented by cupriessineæ, abietineæ, and taxineæ; finally, by Angiospermous dicotyledons, comprehending myriceæ, betulaceæ, cupuliferæ, ulmaceæ, balsamifluæ, salicineæ, laurineæ, thymaleæ, santalaceæ, corneæ, myrtaceæ, calycantheæ, pomaceæ, rosaceæ, amygdaleæ, leguminosæ, anacardeæ, juglandeæ, rhamneæ, celastrineæ, sapindaceæ, acerineæ, tiliaceæ, magnoliaceæ, capparideæ, sapoteæ, styraceæ, oleaceæ, ebenaceæ, ilicineæ, and ericaceæ.

"The Pliocene epoch, considered in relation to Europe, for I have intentionally excluded from the preceding list some fossils of the Antilles referred to these formations, offers as peculiar characters an extreme analogy to the existing Flora of the temperate regions of the northern hemisphere; I do not say of Europe, for this Pliocene flora comprehends many genera strangers in the present time to Europe, but proper to the vegetation of America or temperate Asia. Such are, if we admit the accuracy of the generic relations established by the botanists to whom these determinations are owing, taxodium, salisburia, comptonia, liquidambar, nyssa, robinia, gleditschia, bauhinia, cassia, acacia, rhus, juglans, ceanothus, celastrus, sapindus, liriodendron, capparis, sideroxylon, achras, and symplocos, all genera foreign to temperate Europe, but in which they have been found in a fossil state, but which, for the most part, still occur in the temperate regions of other parts of the globe.

"As to other genera still existing in Europe, but which contain only a small number of species, we find many more of them in a fossil state; such are the _Erables_, of which 14 species are enumerated in this Flora of the Pliocene epoch, and the Oaks, which are 13 in number. It ought to be remarked, that these species come from two or three very circumscribed localities which, in the present time, probably would not furnish, in a circuit of many leagues, more than three or four species of these genera. Lastly, another character, which I have already spoken of, and which makes this Flora to differ still further from that of our epoch, is the absence, or at least the small number and nature of the plants with Gamopetalous corollas.

"Thus, there are only twenty plants of this Flora arranged in the families of this division, and all are referrible to this group of Hypogynous gamopetales, which I have distinguished by the name of Isogynes; in the general organization of the flowers, they approach nearest to the dialypetales.

"Is this absence of Anisogynous gamopetales, and with irregular ovaries, the result of chance; or does it arise from this, that many of these plants, particularly among the species of temperate regions, are herbaceous, and that herbaceous plants are generally in conditions less favourable for passing into a fossil state? Or, lastly, did those families, which some botanists have been led to consider the most elevated in organization, not yet exist? These are points which cannot be positively determined in the present state of our knowledge.

"We may however remark, that at the Miocene epoch, these plants were still less numerous, but belonging to other families; and that at the Eocene period, no one is mentioned by the authors who have shewn the connection between the fossil and living plants, without having any preconceived idea on the subject.

"Another fact to be noticed, but which likewise probably depends on the herbaceous nature of these vegetables, and their leaves not being shed, is the almost complete absence of Monocotyledons, ferns, and mosses, which establishes, in regard to these families, a very great difference between the Pliocene flora and that of modern Europe.

"A difference not less important distinguishes this Flora from that of the most ancient epochs; namely, the absence, in all these formations, of the family of Ferns, which, on the contrary, furnishes so prominent a feature in the Miocene epoch. No trace of them occur in Europe in the Pliocene formations I have enumerated; while the woods of this family are very abundant in the formations of the West Indies, which is considered as an epoch at least as recent as the Pliocene formation, which appears to indicate that at this period the zones of vegetation were distributed nearly as at present.

"Indeed, in these modern formations of the Antilles, we find among the fossil woods, the only portions of their vegetables that have hitherto been collected, specimens which indicate the existence, not only of numerous and varied palms, but of many other families of the equatorial zone, such as Lianes, nearly related to Bauhinia and Menispermeæ, Pisonia, &c. The vegetation of the Antilles had therefore at this period the characters of the equatorial zone, as in Europe it had then the characters of the temperate zone.

"Lastly, and to terminate our observations on this Flora of the latter geological epoch which preceded the present one, we would remark that, notwithstanding the general analogies which exist between the vegetables of these formations and those now living in the temperate regions, no species appears to be identical, at least with the plants that still grow in Europe; and if, in some rare cases, complete identity appears to exist, it is between these vegetables and American species. Thus the Flora of Europe, even at the most recent geological epoch, was very different from the European Flora of the present day."--_L'Institut._

_Glacial Theory of the Erratics and Drift of the New and Old Worlds_.[45] By Professor L. AGASSIZ.

Footnote 45: _Vide_ Lake Superior, its physical character, vegetation, and animals. By Professor Louis Agassiz. 1850.

_Glacialists and Antiglacialists.--Erratic basins of Switzerland.--Similar phenomena observed in other parts of Europe.--Points necessary to be settled; first, the relation in time and character between the Northern and the Alpine erratics.--Traced in North America.--Not yet settled whether any local centres of distribution in America; but the general cause must have acted in all parts simultaneously.--This action ceased at 35° north latitude; this incompatible with the notion of currents.--In both hemispheres a direct reference to the Polar Regions.--Difficulty_ _as to so extensive formation of Ice, removed; difficulties on the theory of Currents, the effects contrary to experience of Water-Action.--Erratic phenomena of Lake Superior.--The Iceberg theory.--Description of appearances at Lake Superior.--Drift; contains mud, and is without fossils.--Example of juxtaposition of stratified and unstratified Drift, at Cambridge.--Date of these phenomena not fully determined, but doubtless simultaneous all over the Globe.--The various periods and kinds of Drift distinguished.--Accompanied by change of level in the Continent._

So much has been said and written within the last fifteen years upon the dispersion of erratic boulders and drift, both in Europe and America, that I should not venture to introduce this subject again, if I were not conscious of having essential additions to present to those interested in the investigation of these subjects.

It will be remarked by all who have followed the discussions respecting the transportation of loose materials over great distances from the spot where they occurred primitively, that the most minute and the most careful investigations have been made by those geologists who have attempted to establish a new theory of their transportation by the agency of ice.

The part of those who claim currents as the cause of this transportation has been more generally negative, inasmuch as, satisfied with their views, they have generally been contented simply to deny the new theory and its consequences, rather than investigate anew the field upon which they had founded their opinions. Without being taxed with partiality, I may, at the outset, insist upon this difference in the part taken by the two contending parties. For, since the publication of Sefstroem's paper upon the drift of Sweden, in which very valuable information is given respecting the phenomena observed in that peninsula, and the additional data furnished by De Verneuil and Murchison upon the same country and the plains of Russia, the classical ground for erratic phenomena has been left almost untouched by all except the advocates of the glacial theory. I need only refer to the investigations of M. de Charpentier, Escher, Von Derlinth and Studer, and more particularly to those extensive and most minute researches of Professor Guyot in Switzerland, without speaking of my own and some contributions from visitors,--as the Martins, James Forbes, and others, to justify my assertion, that no important fact, respecting the loose materials spread all over Switzerland, has been added by the advocates of currents since the days of Sanssure, De Luc, Escher and Von Buch; whilst Professor Guyot has most conclusively shewn that the different erratic basins in Switzerland are not only distinct from each other, as was already known before, but that in each the loose materials are arranged in well-determined regular order, shewing precise relations to the centres of distribution, from which these materials originated; an arrangement which agrees in every particular with the arrangement of loose fragments upon the surface of any glacier, but which no cause acting convulsively could have produced.[46]

Footnote 46: A comparison of the maps, shewing the arrangement of the moraines upon the glacier of the Aar, in my _Système Glaciaire_, with the maps which Professor Guyot is about to publish of the distribution of the erratic boulders in Switzerland, will shew more fully the identity of the two phenomena.

The results of these investigations are plainly that the boulders found at a distance from the Central Alps, originated from their higher summits and valleys, and were carried down at different successive periods in a regular manner, forming uninterrupted walls and ridges, which can be traced from their starting-point to their extreme peripheric distribution.