Imatges de pÓgina

structed, would be paramount over the solar; so that the position of the sun, relative to the equator, would act a very subordinate part in modifying climate, instead of being its sovereign arbiter, as at the present day. Plants which love a warm but humid atmosphere, like the equisetums, ferns, &c., would multiply and flourish, under such circumstances, with nearly equal vigour in the Arctic regions as under the Line!! Hence also the difference of equatorial and polar temperatures would be at first comparatively small, so that a considerable uniformity of vegetation would pervade the most distant zones." We need not, therefore, be surprised at finding the same Calamites or gigantic equisetums buried among the coal-measures of New Holland, (near Port Jackson,) and of England; though now-a-days, that plants are subjugated to the undivided empire' of the sun, they differ in species with very moderate variations of latitude, and with every change of hemisphere.


"The first age of the world then, extending probably through several centuries, fully realized the universal and unfading spring of the poets. Under such fostering powers of vegetation, the coal-measure plants were matured, in countless myriads, with a rapidity to which modern experience can fur nish no parallel. But the tremendous catastrophes of the crust of the earth, that took place soon after this period, of which the dislocations and disruptions of the coal-strata them?? selves exhibit magnificent memorials, generated a vast quantity of detritus from the older rocks, which at first diffused through a turbid -ocean, progressively subsided on its bottom in the chemical order of deposition; constituting beds of conglomerate' limestone, red marl, and lias; in variable proportions of thick ness and extent, according to the nature of the exploded and comminuted rocks. In the secondary formations of geology, in fact, we see nothing but a repetition of mineral triads; shells more or less fractured, covered with a two-fold coat, the undermost of sand or sandstone, the uppermost of clay more or less indurated. The tepid ocean-bed vied in fecundity with the glowing soil round its shores, and thus was

covered with a thick deposit of shell-fish and their exuviæ. At each rencounter of the water and subjacent explosive metals,! these shells would be more or less scattered and broken down, and when tranquillity returned, covered with their siliceous and argillaceous mantles. out ap? silt Lamo1 21536# 9:li lo -The conglomerate limestone and red marl are referred by! geologists (see Conybeare and Phillips) to the detritus of the primitive and transition rocks; deposits just posterior to the coal formation. It is probable that the submarine disturbances 8699 12 slow gift (9) oton

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Ure's New System of Geology.

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dt. : 02: vnioz *vo tu Mareq od bloom b of that particular age were unfavourable to the multiplication of mollusca. But a period of repose seems to have followed, in which the shells of the lias were elaborated. These, with a little alumina, are condensed into the lithographic stone, and buried under a loamy compound of sand and clay. We have next the inferior oolite; merely a congeries of pulverised shells, roofed with the corn-brash, &c., and overlaid with the Oxford clay. Then we come to the coral rag, teeming with vestiges of vitality; inhumed also beneath its sheet of Kimmeridge clay.


"When we arrive at the Portland strata, we must consider that a series of most imperfect conductors of caloric, fully half a mile in thickness, had been by this time interposed between the bottom waters of the sea, and the deeper primitive, or transition crust, on which they originally reposed. za


"The climate of the earth should therefore indicate, about the Portland era, an abatement of the hypertropical temperature of the first age."


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In addition to the results of the successive interpositions of non-conducting media, between the ocean and its subjacent fires, in lowering the surface temperature of the globe, we must take the following phenomena into account. By each series of explosive dislocations of the terrestrial crust, the area of the land standing out of the water' would be abridged; that of the sea would be amplified, with a proportionate diminution of its depth; or, in other words, the cooling surface would be augmented at the expense of the heating surface; while the ocean would come to repose, as we have seen, on a cooler bed, because more distant from the central heat of the earth. These propositions we shall endeavour to place in clear and certain light by an ample induction of facts..




Ina revolving terraqueous sphere, deviating from the equilibrium, form of rotation, by its elevated lands and deep ocean beds, at every considerable disruption and comminution of its surface, the gravitating powers will become effective on the shattered, shell, and arrange its fragments, so as to make the crust approximate more nearly to the geometrical spheroid. The mountain and table-land masses will thus be strewn over the concave bottom of the seas, and cause a new distribution of the waters round the sphere; in which the area of the dry, land will be diminished proportionally to the extent and duration of the disruptions, inongo 992) agizoļons "Supposing the earthquakes, and consequent comminution of the shell, pot partial and successive, but universal and synchronous, then the whole crust of the earth having its cohesion JAN. MARCH, 1829


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destroyed for a season, would forthwith obey the gravitating forces on a revolving sphere, would assume the spheroidal figure of rotation, and remain universally circumfused with water, as under the primordial abyss. But a partial and successive series of disruptions of the crust will cause only a partial approximation to that ultimate figure, accompanied with a transient deluge of greater or less extent over the surface. When the explosive commotions cease, the ocean undulations will subside, the sea will flow back into larger but shallower basins, and the dry land will again appear, furrowed, and strewed over with the detritus of the storm. This view of a diluvial transition, in my apprehension, can hardly be deemed hypothetical, resting as it does on the joint bases of geological facts and physical laws."

"We have therefore every physical reason to conclude that each great antediluvian convulsion of the earth extended the empire of the sea, and abridged the boundaries of the land by a permanent submersion of some of its regions; mechanical effects involving commensurate physical changes of climate; 1. by the thickening deposits of the ocean; 2. by the increase of the cooling or aqueous surface of the globe; and 3. by the decrease of the heating or terrene, as will be fully developed in treating of the deluge in the fifth chapter."

These novel views are resumed, with additional explanations, when the phenomena of the deluge are described.

"The bouleversement involved in these propositions, and deducible from the phenomena on which they rest, must, by the established laws of physics, as we have already shown, have materially increased the area of the ocean, and diminished that of the land. To what degree this change of pro portion amounted, we have no precise data to determine.


On Mr. Penn's principles, the ratio of land to water was inverted by the deluge; for he assumes that our actual seas correspond in surface to the antediluvian lands, and our actual lands to the antediluvian seas. But the researches of Professor Buckland on the Kirkland and Franconia caves, as well as those of Baron Cuvier on the grotto of Oiselles, concur to prove that these were dens inhabited by antediluvian quadru peds; and therefore must have formed a portion of its dry land. Moreover, most, of our coal districts, and primitive schistose mountains, in Scotland, for example, bear no good evidence of having lain under the sea during the long antediJuvian period. A few sheils may no doubt be found scattered over their surface, relics of the deluge; but these marine exuviæ

do not constitute regular testaceous strata in their body, as would undoubtedly have happened during a long residence in the bosom of the ocean. Our coal-measures, indeed, are most probably the basins of antediluvian lakes and marshes.

"With Mr. Penn's proportion of land and water, I conceive the terraqueous globe would not have been habitable by man and his companion animals. It would have possessed nearly three parts of earthy surface to one of aqueous; whereas there is now fully three of aqueous surface to one of earthy. Or, since dry ground is the heating surface, and water is the cooling, the heating faculty of that ancient globe would have been three times greater than the present, and its cooling faculty three times less; making a nine-fold difference in calorific constitution between the two, without taking into account the proper heat of the antediluvian seas. Under such circumstances of heat and aridity, vegetation must have pined, or most probably expired, except in a few narrow bands of soil along the margin of the sea; as is now exemplified on the Barbary shores. If we suppose that only one half of the primeval land perished at the deluge, and that half possibly a great continent, (corresponding to the Pacific Ocean,) which might form the whole world to the antediluvians, unversed as they evidently were in navigation, then the area of their dry land would have been equal to that of their seas; and the general climate of their globe, as far as depended on the constitution of its surface, would have been three times warmer and drier than the present. This by no means implies, however, thermometric and hygrometric degrees three times higher than the present. Besides, the hotter surface of the land would be compensated by a greater radiation of heat into space, and the hotter surface of the seas by a more copious evaporation of water into the air. Still that incontestable physical principle will perfectly account, to a certain extent, for the higher temperature which prevailed in our latitudes in antediluvian times, and for the sudden and vast refrigeration induced by the deluge. I do not presume to define the numerical proportions of land and water on that ancient globe; but I maintain that such a mighty diluvian catastrophe, as it suffered, could not be accomplished by any powers of nature which the laws of inductive logic authorise us to employ, namely, general explosive and disrup tive forces of volcanic origin, without increasing the area of the sea, at the expense of the land. We must moreover keep in view the increasing obstruction of the central heat after each successive catastrophe."

The specimens now exhibited of Dr. Ure's work will recomK 2

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mend it more effectually to the notice and patronage of our readers than the most elaborate eulogium which a critic could indite. The wood-cuts and plates represent a well-selected variety of mineral sections and organic remains. In five copper-plates are figured seventy fossil shells, characteristic of the several great strata from the mountain limestone up to the London clay. There is an exquisite lithographic impression of the petrified stem and leaves of a cactus cylindricus-a fossil which appears to occur very plentifully in a coal sandstone in Ayrshire.


The popularity of Dr. Ure's work will be deservedly enhanced by the consideration that he has triumphantly confuted every cavil of the least consequence, which geological sciolists have urged against sacred history. And all this is done in a truly philosophical spirit without the slightest air of religious intolerance. On the whole, we regard this new system of geology, as one of the most valuable accessions lately made to the scientific literature of our country.


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On some Phenomena of Vesuvius.

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On some Phenomena of Vesuvius.-Extracted from the Journal of, and communicated by OCTAVIUS MORGAN, Esq. bas March 25th, 1828.-Vesuvius had all day been sending forth, at very short intervals, immense volumes of dark smoke, or rather dense vapour, charged with ashes and sand, which were carried in an eastward direction, by a strong westerly wind that prevailed all day, and which fell in showers on the opposite side of the mountain, as was plainly discernible from Naples, darkening the air beneath as they passed. We started from Naples at 7 P.M., and in our way to Resina, and afterwards, whilst ascending the mountain, I saw frequent flashes of sheet lightning, some above the volcano, and others in various directions all around-not seeming to proceed from any particular spot. There was also much hail both on the cone, and down below at Resina. We ascended to the summit without other inconvenience than a very strong wind. On the brink of the crater, the wind was so tremendously powerful that it was utterly impossible to stand; to creep on all fours was our only chance of escaping being precipitated into the


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