the whole there seems reason to think the new red-sandstone system England and France above the chalk a prevalence of green and ferrucould not have occupied a long time in its formation compared to ginous sands extremely similar to those below. Perhaps they have other deposits of equal thickness. [RED-SANDSTONE FORMATION.] been derived from the waste of these older rocks: Sir Charles Lyell Oolitic System.-Into the same European and Asiatic basins which supposes the tertiaries of the London basin to have been formed received the red clays, red sands, and magnesian limestones of the last from the waste of the secondary strata of Kent, Surrey, Sussex, and system, subsequent agencies brought blue clays, sands more or less Hampshire. ochraceous, and limestones characterised by an oolitic texture. These With the tertiary system came into existence (if we may trust the deposits are parallel to the old rocks below, and no trace of any change negative evidence which the earlier strata present) many races of of level in the region where they occur has been noticed in England-quadrupeds, some birds, reptiles, and fishes, extremely analogous, perhaps not in Germany. Must we refer to some distant convulsion though for the most part specifically distinct from the modern denizens for an explanation of the change of sediments, and for the equally of land and water; thousands of corals, shells, Crustacea, &c., which great change, or rather sudden development, of organic life, which present with living races quite as great analogy as obtains between comes in with the oolitic era? New and more abundant forms of the tribes of the Atlantic and the Pacific oceans of our day; the plants (Cycadea), with many varieties of Zoophyta, Mollusca, Crustacea, general features of land and sea as they now exist begin to appear, fishes, and gigantic reptiles of the land, rivers, and the sea, mark the and there can be no doubt that in a philosophical study of the revooolitic rocks, and render them justly comparable, as a system, to the lutions of the globe the tertiary era of geology cannot be properly great carboniferous assemblage of strata. Locally indeed the oolitic separated from the existing system of nature. rocks yield coal among the interpolated grits and shales, just as happens among the rocks interstratified with the older mountain limestone. The resemblance of the oolitic to the carboniferous limestone tracts is extremely great in general features; and the reason is that both are essentially sea-deposits, characterised by calcareous rocks formed in the deep sea, and liable to admixtures of sandstone and shales along the shores. In such situations each is carboniferous. Both are highly rich in oceanic life, but during the formation of the oolitic rocks there is no proof that anywhere such excessive richness of vegetation was renewed on the land as that which yielded the mass of coal-plants in an earlier period. [OOLITIC SYSTEM.] Yet during the deposition of these rocks the relations of land and sea were greatly altered in Europe by the rising of the Pyrenees beyond the height they reached after the cretaceous era, and by the uplifting of the Alps from the Mediterranean towards Mont Blanc. In England we may believe the upward movement of the southern counties, connected with the Hampshire axis of elevation and the Isle of Wight convulsion, was ended before the close of the tertiary period. The eastern range of the Alps from Mont Blanc to Vienna is of later date, and may be viewed as the most marked phenomenon of elevation which accompanied or preceded the dispersion of erratic rocks in Europe. [TERTIARY SYSTEM.] The following table, from Professor Ansted's 'Elementary Geology,' gives a summary view of the various strata of the earth, arranged according to the latest authorities, and also gives the foreign equiva lents of the various British rocks :— Cretaceous System. The last portion of the series of secondary strata was deposited in the same oceanic basins as the earliest as far as Europe is concerned, but this is not the case in America. Generally in Europe the cretaceous rocks have their stratification parallel to that of the oolites, though some uncomformity in this respect occurs in Yorkshire and Dorsetshire; and in the south-east of France dislocations affected the oolitic strata before the production of the cretaceous rocks. But these comparatively slight movements of the bed of the sea appear totally insufficient to account for the complete change in the chemical and mineralogical character of the rocks, and the new orders of Zoophyta and Mollusca which date from the Modern Deposits:— commencement of the cretaceous era. Sands coloured green by silicate of iron, white soft limestones with beds or nodules of flint, seem to bespeak an origin from the waste of other lands than those which discharged other sands into the oolitiferous sea, and other modes of chemical or vital action in the sea; yet a scrupulous analysis of the oolitic system shows in its upper part analogies to the cretaceous rocks so strong and so various as to render it probable, if not certain, that the new conditions characteristic of the new system were gradually or partially introduced till they entirely predominated-for greensands alternate with the uppermost of the oolitic limestones in the Alps, flinty nodules lie in the calcareous grit and Portland oolite, and chalky limestones constitute the great portion of the latter rocks in some situations of England. It is to be regretted that we are so little able to determine upon good evidence what the new conditions influential on the deposits of the cretaceous rocks were; for their effects are very similar along a great range of the Atlantic coast of North America from New Jersey to the Mississippi, and throughout the interior of Europe. British. Table of Classification of Rocks. Raised beaches Newer Tertiary, or Pliocene 1. Upper gravel and sand 3. Mammaliferous crag 4. Fresh water sand and gravel 5. Red crag Middle Tertiary, or Series: 6. Coralline crag Series: 7. Fluvio-marine beds The cretaceous period was not ended in England by dislocations situated in or even near that part of the surface. In Ireland eruptions of basalt of enormous extent cover the chalk, and indicate a crisis of volcanic disturbance. In France, Elie de Beaumont refers to the concluding part of the cretaceous period dislocations which range north-north-west in the Jura, and traverse the primary mass of Mont Lower Tertiary, or Eocene Viso. After the chalk formation was completed in the south of France the Pyrenees were uplifted to a great height, so as to limit the tertiary basins of the south of France; and it is supposed that at the same time the Apennines and the Carpathians experienced an upward movement. Conjecture has even joined to these the Alleghanies; but it may be gathered from Professor Rogers's reports on the geology of America (British Association Reports'), and accordant notices of Featherstonhaugh and other competent geologists, that an earlier date should be allowed to that mountain range. [CHALK FORMATION.] 9. Bagshot and Bracklesham 10. London clay and Bognor 11. Plaster and mottled clays, Foreign Equivalents or Synonyms, and chief Foreign Localities. Similar appearances in Northern Europe, These beds or their equivalents are known in various parts of Northern Europe or America. Other but very different deposits are the newer beds of Sicily. Others again are found occupying a large part of South America. Subappenine beds. Brown coal (of Germany). Belgian tertiaries (crag). The Sivalik beds (India) are supposed to belong partly to this period. Touraine and Bordeaux beds. Part of the Molasse of Switzerland. Certain European, Asiatic, North African, Paris Basin. Central France. Molasse of Switzerland (lower beds). Various beds in Western Asia and India. SECONDARY EPOCH. 12. Upper chalk with flints 14. Lower chalk and chalk Tertiary Periods. In general no contrast can be more complete Cretaceous System :— than that between the secondary and the tertiary stratified rocks: the former retaining so much uniformity of character, even for enormous distances, as to appear like the effect of one determined sequence of general physical agencies; the latter exhibiting an almost boundless local variety, and relations to the present configuration of land and sea not to be mistaken. The organic bodies of the secondary strata are obviously and completely distinct from those of the modern land and sea; but in the tertiary deposits it is the resemblance between fossil and recent kinds of shells, corals, plants, &c., which first arrests the judgment. In general there is a decided break between the two groups of rocks-a discontinuity which is nowhere completely filled. Yet, besides the pseudo-tertiary or transition chalky rocks of Maestricht and the Pyrenees, and the conchiferous marls of Gosau, we have in Scaglia limestones of the Mediterranean. Near Boulogne. North of Germany. Jura limestone is the usual continental synonym of our oolitic series. Lithographic limestone of Blangy. Solenhofen beds. Beds in South of Russia and in India. these changes cannot be completely understood if we leave out of consideration the daily variations which occur in the condition of the earth, nor can the operation of existing agencies be completely represented to our minds without calling in aid the inferences derived from a study of earlier phenomena. One of the most important things ascertained by geological investigation is the certainty that the operations by which stratified rocks were formed in the sea-bed, and the igneous rocks uplifted from below, were repeated nearly in the same succession over most parts of the globe. Some of the formations are very extensive: in all countries the lower strata are of the character of gneiss, micaschist, slate-rocks, &c. These primary strata may almost be termed universal: the organic forms which they contain, though few, are very similar, or exactly identical, over enormous areas; and there can be no doubt that during the deposition of these ancient rocks the earth enjoyed an uniformity of conditions over its surface never since Étage Bathonien is the name given by repeated. There is no proof that land existed anywhere in the earlier Nerinean limestone. D'Orbigny to our lower oolites. Calcaire à polypiers. Calcaire de Caen. Calcaire à gryphites. Keuper marls, or Marnes irisées. Bunter sandstein, or Grès bigarré. PALEOZOIC EPOCH. Zechstein. Kupfer Schiefer and other shales. The coal-measures occupy an important Russia, and also in North America; in British Islands. The Kiesel Schiefer of Germany is an The Belgium limestone beds and others Devonian beds are well known in Belgium, varia. part of this period-no probability that any part of our continents or islands then stood above the water. At the close of the primary period the effect of elevatory forces was manifested by the existence of some narrow ridges and peaks of rocks, corresponding to some of our present mountain tracts, as the Grampian and Cumbrian mountains, and of others now vanished, which nourished the forests and herbs whose destruction has yielded coal. Through the secondary period this elevation of land proceeded gradually, or by intermitting action, till at the close of that period some of the principal features of European geography were visible; the ocean was contracted and divided into many basins and gulfs, some of which remain, as the Adriatic, English Channel, German Sea, &c.; while others, as the Vale of the Danube, Sea of the Rhine, &c., have been dried by further elevation. The same elevatory action continued through the tertiary eras completed the geographical features of Europe, and though we cannot trace so minutely in other parts of the world the contemporaneous changes, enough is known to assure us that the same causes have, within the same general limits of time, produced, in all quarters where dry land appears, the same phenomena. In the preceding pages we have spoken of the elevation of land from the sea as a thing perfectly well understood, and admitted as a basis of reasoning. It is so admitted by geologists of every shade of opinion who wish to explain effects by real causes. We shall here present a short sketch of the reasons which have produced on this important point so general an agreement among geologists. 1. In existing nature the combined influence of the exterior and interior causes of change cannot materially affect the level of the sea (as estimated by the mean radius of its surface). Within sensible limits the sea-level is now permanent. 2. The land now above the waters was formerly below them, and could only have been laid bare by the elevation of parts of the sea-bed, or by the abstraction of the ocean to other regions, either through depression of its bed or through a displacement of the axis of rotation, or by an universal diminution of the quantity of water on the globe, or by a change of the oceanic level through great alterations of temperature at the surface or through the mass of the globe. In examining these possible modes of desiccation of land, geology must have recourse to collateral science. The two last hypotheses, namely, of a change of oceanic level, without change of external form or axis of rotation, are insufficient for the purpose. Sound reasoning rejects the supposition of an indefinite waste of oceanic waters for miles in depth, because the position of our planet in space yields no escape for the water; nor is there any ground for believing that the quantity fixed in mineral compounds since the date of the earliest strata is of much importance. A general change of tempe rature of the globe would certainly alter the relative level of land and water, because their rates of expansion and contraction are unequal. Between the boiling heat, 212°, and what is probably below the mean temperature of the actual seas, 40°, the contraction of the water would be about 042 of the whole quantity. The land certainly would contract less, and thus by a general cooling of the globe the ocean-level would relatively sink. To put the case to extreme, we shall suppose the contraction of the land 0, the area of the water to remain unchanged, and the mean depth of the sea ten miles; the reduction of level of the ocean would be of a mile = 739 yards. have been found in Brittany, in West-Now, as all the conditions of the problem have been taken in extreme, fossils to those found both in the Herefordshire. The paleozoic beds of raneous. Silurian strata extend over much of the phalia, near Constantinople, and in Asia Lower Silurian series:- According to every view of geological causes and effects, the present aspect of our planet is the result of all its previous changes; = as the deepest part of the sea probably does not exceed ten miles, as one quarter of the spherical surface is land, and the area of the sea must diminish as its level sinks, it is very obvious that the greatest possible change of oceanic level from this cause could only go to one, two, or three hundred yards at most; and therefore it is impossible by such means to explain the desiccation of land from 1000 to 10,000 or 20,000 feet high. Moreover, during this cooling of the land and sea the whole globe would contract; and from this cause the mean radius of the ocean diminish and its mean depth augment, so as to reduce still more the possible extent of land that could be drained by its change of dimensions. The attraction of the ocean to other regions would lay dry parts of its bed; and if astronomical science permitted geologists to change at their pleasure the position of the axis of rotation of the earth, few difficulties need stop the career of speculation; but the earth is a spheroid of revolution, and if the attraction of the heavenly bodies in the various positions which it takes with regard to them does not disturb its axis of figure, neither can it be thought that the volcanic fever of its surface can so alter the interior densities as to cause any sensible change in this respect. But that the bed of the sea may have sunk, that other continents than ours may have fallen below their ancient level, may be assumed as readily as the rising of the existing land, but with this restriction, that the sinking of the bed of the sea requires to be far greater than the rising of the land, because three-quarters of the globe are covered by water, and thus a small difficulty is overcome by introducing a greater. Frequently however this dependence of the form of the existing land upon the ranges of mountains is disguised by the extent of comparatively plain country which separates the mountains from the sea. Thus, all the eastern half of England might seem to have its form independent of the narrow ridges of the western mountains; and it is but a vague relation which links the Baltic, the Black Sea, and the Caspian to the Harz, Saxon, Carpathian, Caucasian, and Uralian chains. In these and many other cases it is necessary to admit that the general level of the sea has subsided, or that large tracts of land have been raised gradually, or by successive movements round the mountains, which in earlier times were uplifted by more violent effects. The diagrams, figs. 2 and 3, illustrate the fact of the general slope of the English strata from the western mountains; but this cannot be explained by the violent elevation of these mountains, for α d e h g Fig. 4.―a, Red marl; b, lias limestone; c, lias clays; d, lower oolite formation; e, Oxford clay; f, middle oolite formation; g, Kimmeridge clay; h, upper oolite. Finally, on turning to the phenomena connected with mountain chains, it is per fectly certain from the position of the strata often vertical or contorted in the sides of chains, highly inclined near them, and gently sloping at greater distancesthat these rocks have been displaced by an elevating force acting from below. The direction of the force, the geological time of its occurrence, its sudden or gradually accumulated intensity, and many other characteristic circumstances, can be deter mined; and upon the whole no doubt remains that elevating movements have raised the land, and there is no reason to deny that depressing movements may have sunk the bed of th sea. Throughout all the globe the outlines of land and sea depend principally on the disposition of mountain chains and groups, which in every instance yet known are certainly shown to have been raised by mechanical agency, generally with a degree of violence so great as to require the supposition of great and general ex citement of the subterranean forces of heat. America, for instance, derives its form from the chains of the Andes and Rocky Mountains, the littoral range of Brazil, the Alleghanies, &c., mountains Fig. 5.-a, b, c, d, e, f, have the same meaning as in Fig. 4; 111, mmm valleys which descend with the slope of the strata, here supposed to dip south; NN, and P, longitudinal valleys, or such as run parallel to the outcrop of the strata; T, a transverse valley, uniting the longitudinal ones. d d Fig. 6. The letters have the same signification as in Figs. 4 and 5. probably of very unequal antiquity. The Ghauts define the western side of India, as the Atlas mark the north-western border of Africa; the Pyrenees and Sierras give the form of Spain; the Cornish, Welsh, Cumbrian, Lammermuir, and Grampian ranges explain the figure of England and Scotland. b this happened principally before the deposition of the coal strata. A large area round these mountains has since been gained from the sea by more gradual changes of level. Similar phenomena present themselves in detached areas all over the world; but in very unequal degrees, and with unequal differences of level above the ocean, even in neighbouring tracts. It appears therefore more probable that particular regions have risen round the same points and lines which once experienced a violent upward movement. There is no reason to deny that the oceanlevel may have been somewhat lowered by the subsidence of a part of its bed; but it has been already shown that no reasonable (perhaps no possible) sinking of the ocean-bed could explain the phenomena of the desiccation of even the flatter parts of the land. The interior features of every country, in like manner, depend upon recognised geological agencies. The unequal elevation of mountain ranges above the sea is а phenomenon which will be found of great importance in geological theory. It appears to be true, at least in Europe, that the most elevated chains of mountains are those whose elevation was not ended (if, indeed, it be yet ended) until the tertiary or later epochs. Thus, the Alps, which bear on some of their heights (Diablerets) caps of tertiary strata, ascend to 15,660 feet above the sea; the Pyrenees, whose principal elevation appears to have followed soon after the chalk, to 11,270; the Carpathians, nearly of the same date, to 8675 feet: while in the Harz the older mountains (Brocken) rise to 3739 feet; in Wales (Snowdon) to 3675 feet; in the Grampians (Ben Nevis) to 4350 feet. The highest point of Norway (SchneeHaten) more than 8000 feet above the sea, but there can be no doubt that violent as well as gradual upward movements affected the Scandinavian ridges to a late geological era. Raised in this manner by violent or gradual movements out of the sea, the dry land has since been subjected to waste by atmospheric action; and there is no doubt of the truth, that to different sorts of rock belong some differences of aspect, some characteristic scenery. The forms of the hills and valleys are not the same in the gneiss and mica-schist of the Grampians; the clay-slate ranges of Wales; the limestone of Derbyshire; the oolites of Gloucestershire; the chalk of Wiltshire; even single rocks and waterfalls have distinctive characters, and the whole aspect of a country changes with its geological structure. It thus appears that the nature and structure of the rocks, their elevation above the sea, and the manner in which they attained it, and the intensity and duration of the atmospheric agencies which have since affected them, are the elements which determine in every instance the physical aspect of a country. No question in geological theory has been the subject of so much debate, with so little of correct reasoning, as that of the origin of valleys. By Dr. Hutton it was contended that atmospheric agency and running waters had excavated valleys; by De Luc the subsidence of the crust of the earth was invoked; Omalius D'Halloy introduced the consideration of dislocations on the line of the valley; and Dr. Buckland appealed to the overwhelming force of a general flood. None of these views is entirely wrong; each contains partial truth; and the complicated problem of the inequalities of the surface of the earth can be solved by combining them. By violent elevation from the sea, rocks of whatever nature or structure, must have been variously broken and fissured. It is conceivable that some of these fissures might descend below the level of the water. During the elevation some considerable effect on the forms of the ridges and hollows would be produced by the agitated water, but the smaller modifications which they have experienced must be ascribed to atmospheric agency. In these few words we have the history of the rough hills, abrupt valleys, and deep lakes which belong to mountain chains like the Grampians, Alps, and Pyrenees. By gradual risings or interrupted lifts of the bed of the sea, other phenomena would arise; the action of the sea upon the rocks, successively brought within the sphere of its littoral movements, would concur with the form of pre-existing land, and the entrance of its drainage waters, in extending the old and producing new valleys. the next diagram (fig. 6) the same country is represented as rising out of the sea, which penetrates by the transverse valley across the ridges of rocky hills, and flows round them up the vales of clay; its waves wasting the clays under the cliffs, and causing the top to fall, exactly on the same principle that waterfalls at this day, by wasting the argillaceous basis, break down the crowning limestone beds throughout all the north of England. The Giesbach, on the lake of Brienz, compared with the Staubbach; Hardrow Force in Yorkshire, or Ashgill Force in Cumberland, contrasted with the Fall of Lodore, near Keswick, are in this respect very instructive; nor should the cases be neglected where, as on the coast near Scarborough, Robinhood's Bay, and Whitby, the sea now flows among the lias and oolitic rocks, and wastes their argillaceous parts on a small scale, almost exactly as in the above explanation it is supposed to have wasted the similar but thicker clays, when the whole system was rising above the waves. Pleasing illustrations of this kind of action occur in the Medlock at Manchester, the Greta near Ingleton, the sea-coast near Heysham, Sunderland, Berwick, &c. In the Isle of Wight the fresh-water limestones and clays, and the various beds of the plastic clay series about Culver, offer abundance of curious examples. The same mode of action is traced in the forms of mountains and hills which are composed of strata of unequal resisting power; as mountain limestone and shale in the Yorkshire dales, oolite and clay in the Gloucestershire Hills, Normandy, or the Jura mountains. The diagram (fig. 7), given below, represents a cross-section of Wensley Dale, which for a great part of its length exhibits, wherever a considerable rock of limestone comes to the surface, a decided projection and terrace on the hill side, and below every such rock a slope formed in the alternating shales and thin sandstones. How much of this appearance is due to atmospheric action and rain since the river Yore has been running in its present bed, and how much to the influence of water bathing the hill breasts at higher levels, is not easy to determine; but the correspodence of the strata on the opposite sides is such as to leave no doubt that all the vast space of the valley has been really excavated out of continuous strata; and the survey of the whole line of this and other rivers appears to refute the opinion that the existing drainage waters have carried off much of the detritus. To conclude this brief notice of the origin of the principal inequalities on the earth's surface, it may be proper to remark that the view here given of the excavation of valleys at the time of the rising of rocks from the sea, explains the otherwise unintelligible phenomenon of dry valleys in chalk, oolite, and other calcareous strata, which The greater number of these extended or new valleys would be wind and unite like the branches of a river, and have slopes and directed at right angles to the axis of elevation in progress, and there- features such as to prove their origin from moving water, but contain fore, on the dry land, the greater number of valleys originating in these no trace of a stream, no mark of a spring, and often no alluvial circumstances will be found to run with the dip of the strata. How sediment. exactly this agrees with the general character of the drainage channels of the secondary strata of England above the red-sandstone requires only to be mentioned; and it has been already shown that in all the south-eastern parts of England where these strata occur there is sufficient evidence that the elevation of these rocks was due to gradual and long-continued, not violent and transitory movements. While such gradual movements occurred, and strata of unequal hardness and different structure (as limestone and clay, or sandstone, in diagram, fig. 4), were brought within the range of littoral action, these would be unequally affected by the tidal and other currents; the softer parts would be worn away, the harder remain; and thus the red marl would be wasted parallel to the coast-line, or to a certain depth in the water, below the cap of lias limestone; the lias clays would yield beneath the crown of lower oolite; the Oxford clay be excavated below the middle oolite; and the Kimmeridge clay form a vale between the middle and upper oolites. The exact conformity of this with the appearance in nature is well known. The general character of the actual drainage, as Dr. Smith has often and elegantly explained, may be represented in diagram, fig. 5, where ill and m m m are valleys descending on the slopes of the strata, N N and P, valleys formed in softer strata parallel to the coast; T a transverse valley uniting the others. It appears also necessary to remark that, independent of the facts here stated, there must be some importance attached to the effects likely to be produced by the violent agencies, whatever they were, to which the origin of diluvial phenomena is ascribed. The essential thing however in this case being a relative change of level of land and sea, the result of the watery agitation could only be to modify in a greater or less degree the more considerable effects of previous agencies of longer duration. Gravel heaped in particular places conceals some of the earlier slopes of land, and covers with irregular hillocks an original sea-plain, but the great features of the country remain comparatively unaffected by these transient disturbances. Life on the Globe.-Geology enables us to behold, in the present varied and complicated arrangement of land and water, the result of many and repeated actions of causes which are not yet extinct, but continually occupied in similar operations, in different situations, and under different circumstances. The land which has been raised from the sea by internal expansion seems to be slowly wasted away by the action of water, and again restored to the deep. But new land is formed by these ruins, and volcanic fires are yet competent to raise or depress the bed of the sea. The land is not all of the same antiquity; some regions must have been covered by trees, perhaps or rather certainly traversed by quad rupeds, before the substance of others was laid on the bed of the sea. Since life was developed on the globe, if geology has rightly interpreted the monuments of nature, there has never been any considerable period during which the land or sea was wholly deprived of organic beings; but as the condition of the globe changed, the forms of life were altered, old races perished, new creations were awakened, the sum of animal and vegetable existence was continually augmented, and the variety of their forms and habits continually multiplied, as the conditions of land and sea were diversified, until man was added to the wonders of creation, and historic time began. If then, through all past geological time, organic life has changed its aspect as physical conditions varied-if the present physical aspect of the globe is derived from previous physical revolutions, must we look on the present system of organic being, adapted to the present physical conditions, as similarly derived by corresponding revolutions from earlier systems of life, corresponding to earlier states of the land and sea? If the physical aspect of the globe is now changing, does its organic enrichment vary likewise; or is the relation of organic life and physical condition one of coincidence merely-one of those adjust ments independent in its nature, though associated in time and situation, which offer the most convincing proof of continual superintendence of the divine lawgiver of nature? Though we cannot here enter at large on a subject which requires the details which are found under another head [ORGANIC REMAINS], there are points of too general importance, in reasoning on the present condition of the globe, to be wholly omitted:-1. The relation of form and structure between the living and extinct worlds of life; 2. The distribution of the existing forms of life, in reference to the geographical features and geological history of different parts of the globe. The relation of living to extinct races of plants and animals is various. In number, the Recent Flora is perhaps 100 times as considerable as the Fossil Flora, and though this is in some degree owing to the circumstance that land-plants, insects, &c., must necessarily be comparatively rare in marine strata, yet the vast number of individual plants accumulated in coal tracts does not appear to justify a very high estimate of the variety of specific forms of plants in early periods. The same is true of the marine races of shells, Crustacea, fishes, &c.; for both the total number of species, and the relative number to a given thickness of strata, augment from the early towards the later formations, and are greatest of all in the tertiary strata, which in character of organic life most nearly resemble the modern productions of nature. On comparing the living with the vanished tribes of plants and animals, we are struck with the fact that hardly one species of the fossil kingdom is so peculiar in its structure that nothing at all like it is now in existence. Recent analogies of extinct forms are continually and unexpectedly presented to us by the attentive voyagers who now explore the most remote and unknown regions of the land and sea, and continually revealed to us by the discoveries of comparative anatomy, which detects in common forms traces of analogies to extinct creations formerly altogether unsuspected. Thus the belemnite, the trilobite, the ichthyosaurus, are reduced to their proper station among Mollusca, Crustacea, and Reptilia, and the whole extinct and living world of nature becomes united into one general system. But this indubitable affinity between the plants and animals now living and those which adorned the world in earlier ages does not require us to adopt the speculations of Linnæus, Oken, Lamarck, St. Hilaire, and the anonymous author of the 'Vestiges of the Natural History of Creation,' that specific forms of plants and animals are no further permanent than the circumstances which surround them; that as these change those vary; that the immense variety of organic structure may have been derived from a few primitive types-the living gavial from the fossil Teleosaurus, the living cuttle from the fossil Belemnosepia, the living from the fossil Equiseta. This doctrine, plausible as it seems, and flattering as it is to that propensity in man to derive everything from a beginning of which his own senses may give some notion, must be rejected for three reasons: 1. In existing plants and animals the experience of mankind, for 2000 or 3000 years, has shown no essential change. 2. There is no proof, drawn from examination of fossil reliquiæ, of this assumed change from one species to another, much less from one genus to another. On the contrary, it is a very striking truth, illustrated in almost every group of fossils, that while the same species retains through many deposits of different age its essential characteristics, new ones come into view in many of these strata, not by a gradual change, but by a sudden development. 3. The destruction of old races and the introduction of new appear in many cases to have been sudden and complete, at least locally. In considering the distribution of existing forms of life, with reference to the geographical features and geological history of different parts of the globe, we cannot avoid being struck with the fact that each species, each genus, and often each family, of plants and animals, is especially abundant in and often exclusively confined to particular parts of the land or sea, even among those animals whose powers of locomotion are the greatest. Among fishes, birds, and swift quadrupeds, this attachment to locality is scarcely less remarkable than among Plants, Zoophytes, and Mollusca, which have no means of diffusing their races, except what winds and currents give. It has therefore become an admitted truth in the philosophy of natural history, that there are certain regions of the land and tracts of the sea for which particular groups of plants and animals were specially created, and to which for the most part their existence is still confined. The living species of plants and animals which most nearly resemble fossil races are variously distributed over the globe. Tree-ferns, gigantic Equisetacea, and other plants illustrative of the Flora of the carboniferous period, may be found in Brazil, the Indian Islands, and Australia; coniferous plants occur in colder latitudes, or at greater heights in the tropics, as well as in the lias; Cycadaceae occur in South Africa and Australia, and tropical America, as well as in the oolites. The recent Trigonia and Cerithium giganteum are found on the Australian shore; Pholadomya was washed on the island of Tortuga : and Cucullaa belongs to the Indian Ocean. Lingula is found in the Moluccas; but Terebratula in all seas: the nearest living form to the old fossil crocodiles inhabits the Ganges; while the bony pike, whose scales resemble those of Megalichthys, lives in Lake Ontario. Geological Time.-There is perhaps no more difficult problem in geology than the determination of the length of time which has elapsed during the formation of the whole or any definite part of the crust of the earth. Time, as measured by generations of men, fails to carry us back to remote geological epochs; man is but a recent visitor of the globe; compared even to the secondary strata his date is of yesterday, for all the existing forms of life cease with the lower tertiary rocks, only small proportions of them occur in the middle of that series, and traces of men have nowhere been seen in any but the most modern parts of the stratified masses of the globe. If then the history of the human race does not commence till after the deposition of at least the greater part of the tertiary strata, by what rules shall we attempt to compare the few thousand years of his existence with the earlier periods of the history of the globe? In a vague sense, nothing appears more obvious than the conclusion universally admitted among geologists, that the earth is of vast antiquity, yet nothing more eludes the grasp of reasoning than the seemingly easy task of computing its age. The rocks are indeed full of monuments of time, "rudera longinqui sensim præterlapsi ævi,” but we have not yet learned fully to decipher them. When we behold thousands of strata piled on one another in a regular series, each distinct by some peculiarity from the others; when we find among these the original products of chemical action (as limestone), the slow sediments from gentle motion (clays), rough sand and pebbles implying greater agitation; how can we refuse to admit that long time elapsed during the often repeated change of chemical and mechanical agencies of water over the same portions of the bed of the sea? When among these strata we observe the remains of plants and animals, various in their kinds, regular in their distribution, so as to prove that at successive times the same part of the sea nourished successive races of animals, and buried in its sediment distinct races of plants, where in modern nature is it conceivable that such repetitions of change, in all the ranks of creation, could take place except by the aid of almost immeasurable time? Descending to minuter inquiries, we find some particular strata composed of fragments derived from a more ancient rock, which after being deposited in water, was indurated, raised to the surface, wasted by drainage, and again collected in rolled fragments on the bed of another sea. The trees which are imbedded in certain rocks (coal-measures, lias, Portland oolite, &c.), are often known by their rings of growth to be some decads of years old, and in particular cases (Dirt-bed of the Isle of Portland) it is supposed that their whole existence passed between the formation of two beds of stone. Every country affords examples of certain fossil shells confined to even a thin layer of shale, sandstone, limestone, or ironstone, and in some instances (near Leeds and Bradford) the youngest embryo Goniatites and the oldest full-grown shell are found in one bed of 6 or 12 inches thickness, in that alone, and apparently in the place of their quiet existence, so as to indicate that the lifetime of that Goniatite (G. Listeri) was consumed during the accretion of one calcareous bed, which is about th part of the thickness of the coal-measures whose history it enriches. If again, among those strata produced by watery action we find alternations of volcanic rocks, and learn that at particular epochs in the series of deposits mountains were raised from the sea, land clothed with forests was submerged, and the physical geography of particular regions entirely changed, we see clearly that such repeated revolutions of nature agree with the history of the organic creations in refuting the narrow views of those who would limit the age of the world to the short annals of mankind. But how are we to proceed further, so as to clothe with a more philosophical character these almost poetic notions of the immensity |