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within about a mile and a half of Queenston; from which distance to the gorge of the chasm it occupies a retreating cliff, almost, if not altogether, unapproachable. The inequalities, however, of the brow of the mountain, about Brock's Monument*, and along the summit of the cliff, relieve us from these difficulties. The broken platforms and short ledges of this brown limestone which here prevail, shew it to be at least seventy feet thick. It is full of encrinital fragments-many of them coloured of a fine red, like those of Lockport, on the south shore of Lake Ontario. The large bicarinated terebratulæ of Lake Erie are not uncommon; and the debris of indeterminable trilobites, similar to that of Lakes Huron, Sincoe, and Ontario.

I saw many turbinoliæ, ramose millepores, retepores, cellular madrepores, one turbo, and well-marked productæ. The suture-like fissures noticed at the Falls are met with; and, I think, in the same stratum. I did not see here one nodule of gypsum or of silex: but the limestone of the Ridge, one mile and a half west, at the same height, has numerous irregular cavities, lined with crystals of quartz and calcspar; and imbedded in it are the hollow encrinital moulds before spoken of, and a few turbinoliæ, In the lower layers here, too, are the fragments of trilobites, with terebratulæ, corallines, &c.

Examining the Ridge at Wolverton's, thirty miles hence, and a mile or more west of the village of Grimsby, I found no change whatever in this limestone; but I saw none of the nodules above mentioned, probably from the layers in which they chiefly prevail being concealed by herbage. The rock on which this brown limestone is placed, is a black argillo-calcareous shale. It is visible throughout the chasm; along the face of the Ridge to Grimsby, on the west, it can scarcely be seen, for the herbage covering it, nor did I meet with it. I think it positively wanting at Wolverton's. The continuation of those heights easterly, display it in many places; among which Lockport and the Genesee Falls are the best known.

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It is very shaly at the Falls of Niagara, but has browner layers, six to twelve inches thick, interleaved at regular dis

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This fine column is near the highest part of Queenston Heights,

tances. It is homogeneous, and effervesces on exposure to acids. It is often spotted yellow by sulphur, which, under the arch of the Falls, may be gathered in tufts of very small acicular crystals. On this river, and in its vicinity, it does not contain a trace of animal or vegetable life; but at the two places above spoken of, it abounds with new and important kinds of the former, as well as an abundance of the more common. The thickness of this stratum has not been ascertained on the river Niagara; nor can it be, I think, without much trouble and expense. Its inferior connections have not been examined at this place, further than to determine, that the next rock succeeding below is a series of sandstones, which I shall immediately proceed to describe; leaving the additional facts respecting the calcareous shale to be brought forward when on the geology of Lake Ontario.

These sandstones are found throughout the country, west and south of Lake Ontario, little changed in mineral characters or geological position. I do not think that their contents, if thoroughly examined, would present any great differences; but at present, certain organic remains seem to be confined to particular localities. They are every where distributed into the following subdivisions. The first species (from above) is a grey, or white quartzy sandstone ("ferriferous sand rock" of Eaton). It is followed successively by a red argillaceous slaty sandstone, (" ferriferous slate" of Eaton ;) a hard, grey caleareo-argillaceous sandstone, ("grey band" of Eaton ;) and a soft red and green argillaceous shale, to which Mr. Eaton restricts the property of being saliferous, and names it "saliferous rock."

I am inclined to consider all these strata, and their superincumbent limestones, to have been deposited nearly at the same time. They are all conformable to each other, and rarely betray marks of disturbance at the connecting planes. The contained fossils indicate no change of era-the two upper sandstones sometimes alternate. All these sandstones are finely displayed at one place or other in the chasm; and best on the American side, in the middle and lower parts. Near the Falls, the debris of the surrounding cliffs creeps up nearly to the top of the black shale, and only permits a little of the

red sandstone to appear at the water's edge; but about the whirlpool, and especially opposite the Old Mill, the brown, black, grey, and red stripes in the mural precipice point out, in a clear manner, the size and relative position of its component strata. They are also well seen on the east side of Queenston Gorge, where, particularly, the saliferous shale comes into view, and supports the villages of Queenston and Lewiston, in abraded banks, eighty feet high.

The grey sandstone is a grey or greyish white aggregate of uncemented grains of quartz, here and there spotted with ironrust. It is in very thick strata, and is best seen in the face of the heights close to Queenston, where it is quarried. Mr. Eaton found it to be fourteen feet thick here, and in the river Genesee. It contains no fossils.

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This rock is hard, breaking into thick, shapeless, or squared blocks. "In some places, it alternates with the red rock below; but generally they are separated by a continuous layer, or extensive bed of argillaceous iron ore," (Survey, p. 120,) as at Niagara, according to Mr. Eaton. The red argillaceous sandstone beneath this rock is very shaly. It is often soft and almost homogeneous; but frequently, in the contiguous layers, it is harsh and granular. It is about twentythree feet thick, (Survey, p. 121;) its colour is principally red, variegated in clouds, spots, and circlets, with green and blue colours, which occasionally occupy considerable thicknesses of the shale. It is extremely ferruginous, both as disseminated generally, and in bluish-black knots, with a semi-metallic lustre. It contains terebratulæ, both large and small; and a fossil which resembles somewhat the orthocera annulata of Sowerby; but it varies from it in being much more narrow, in having its sides compressed into a quadrilateral form, and in being traversed by minute and numerous ridges. Casts of shells, apparently unios, in red sandstone, are common. The calcareo-argillaceous sandstone, occurring next, evidently belongs to the saliferous formation, like a similar stratum at Runcorn and Manley, in Cheshire.-Geol. of England, Coneyb. and Phill., p. 280. It is here a moderately hard granular rock, chiefly of quartzose materials.. It is white, chequered with flakes of green. It is thin, but is continuous.

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on the east for 200 to 250 miles. It is only eight feet thick. here. It contains exquisitely fine lingulæ mytiloides, in which the original shell is beautifully preserved. There also are many thick white casts of shells, of the unio family. The variety of orthocera, above noticed, is also found here in white casts. The two latter, and the terebratulæ of the red sandstone, are found near Grimsby.

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The red saliferous rock, principally argillaceous, occupies the lower seventy or eighty feet of the Gorge of Queenston, and extends a considerable distance into the expanded river below. Its mineralogical characters are quite the same as at Salina, on the south of Ontario; and as at St. Catharine's and at Saltfleet, near the head of that lake. At all these places, its geological relations are the same. At the two latter, it appears at the foot of the "Parallel Ridge," which is composed of the same materials as in the chasm.

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This rock presents no peculiar characters on the river Niagara. It has been most fully studied by Mr. Eaton on the borders of Lake Ontario. I therefore refer the reader to! its description in the paper on Lake Ontario, where the Saltworks of St. Catharine's and Saltfleet will be more appropriately introduced than here.

JOHN J. BIGSBY.

On the Relation between the Density, Pressure, and Tem perature of Air; and on Experiments regarding the Theory of Clouds, Rain, &c.; with a Conjecture about Thunder and Lightning. By HENRY MEIKLE, Esq.

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[Communicated by the Author.]

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FEW things, I presume, would tend more to facilitate and pro-. mote the study of pneumatical and meteorological science than an acquaintance with the relation between the density, pressure, and temperature of air. Preparatory, therefore, to entering on the consideration of some meteorological phenomena, I submit the following attempt towards investigating. that relation.

1. It was inferred from Boyle's experiments, and subse

quently confirmed by others, that, under the same temperature, the elasticity or pressure of air is as its density, or inversely as its volume; and, consequently, while air undergoes the same change of temperature, its volume varies under a constant pressure, precisely in the same proportion as the pressure would do, were the air confined in an inextensible vessel,

2. Mr. Dalton, M. Gay Lussac, &c. have ascertained, that on heating air, under a constant pressure, from 32o F. to 212° its bulk acquires an increase of three-eighths. Such increase in the air-thermometer is divided into 180 equal parts, or degrees, for Fahrenheit's scale; and the like divisions, corresponding to equal variations of bulk, are continued both above 212 and below 32°. Now, as three-eighths to 180°, so is the whole bulk at the freezing point to 480°; and, therefore, there cannot be more than 480 degrees below 32° on the Fahrenheit scale of an air-thermometer; for by taking 480 such equal parts from the bulk, the whole would be exhausted*.

3. The freezing point being marked 32°, it is obvious that 480° below this will be at-448°. The bulk of a given mass of air, therefore, under a constant pressure, varies as its temperature reckoned from -448°, according to the common graduation; that is, as 448° +t. The degree indicated on Fahrenheit's scale being t. Hence, by art. 1, the pressure of air confined in an inextensible vessel likewise varies as 448°+t.

4. It has been more recently found, that, whilst air undergoes the same alteration of temperature, the change in its quantity of heat is one-third greater under a constant pressure than if confined in an inextensible vesselt; also, when the

* Hence, unless we make the incomprehensible supposition, that air may contract by cooling, till its volume be less than nothing, the absolute zero, if such a thing exist, cannot be lower than-448° F., with reference to the common graduation of an air thermometer; no matter what relation the degrees bear to true ones. But however clear this may be to most people, Mr. Ivory's new law of condensation and rarefaction, to be shortly noticed, recognises no such limitation; but readily produces a cold of thousands of degrees below the impassable limit of that very scale which he maintains to be the true one. In short, his law is fraught with contradiction, view it which way we may. This shews the propriety of examining and trying the consistency of everything, even though it should have issued from an oracle.

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Omitting this property, all that is contained in the first six articles would hold, without regard to the nature of heat, provided the experiments, especially those to be after noticed, be correct.

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