verge, until they all met in one common centre-the centre of the earth.

Now, it must be obvious, that upon a surface so diversified by elevations and depressions, or, in other words, so uneven as that of the earth, where the depth subjected to geological examination is so insignificant when compared with the radius, and when it is considered, that the researches which have revealed these igneous protrusions, and have led to the construction of those sectional maps, have been made in some of the least level parts of the earth's surface-the natural inference to be drawn from all these circumstances is, that no single cause could have occasioned any mineral matter, in a state of fusion, to have observed so uniform a direction on such a diversified surface throughout the whole of a spherical body.

The origin of this uniformity of course must be sought for, not in one, but in a combination of causes, which, unitedly, may be considered commensurate with the effect.

To account for the origin of that which, while it is everywhere the same on the surface of a spherical body, affords symptoms of having travelled thither, we are constrained to look to the centre; and, moreover, the imaginary prolongations of these trappean and basaltic dykes point towards the same direction. Nevertheless, we deny that there resides at the earth's centre any cause or power adequate to have sent forth these streams of melted mineral; a denial which will appear more just, after we have perused the observations immediately following.

While we acknowledge the necessity of looking towards the centre for an effect which is everywhere alike on the surface, and while, at the same time, we set aside the centre itself of the earth as the site of the common cause; and while, in lieu thereof, we consider the centrifugal impetus, arising from the protorotation of the earth to have been the primum mobile of these protrusions; we profess our belief, that neither could centrifugal impetus alone, have given direction to them. Streams of melted mineral matter proceeding solely from, or what is equivalent, in straight lines from an axis of gyration, extending the whole semi-diameter of the earth, must have cut the concentric shell in degrees of obliquity, according to their

parallels of latitude. This, had it taken place, would neither have fulfilled the design which the benignant Creator had in view, nor have caused the protrusions to run in the direction in which they are seen by geologists actually to do. The same difficulty will be felt, even should we add to the above position, the fact of the upheaving or tilting, out of horizontality, of the strata by the same centrifugal force; as it will appear evident, after a little reflection, that veins proceeding in perpendicular lines from the common radius of gyration, the axis of the earth, would (in this latter case) have cut the strata, especially those within the tropics, in directions nearly parallel to the upheaved posture which their lines of stratification had then assumed.

We have ever maintained, that the first rotation of the earth around its axis occasioned a sudden, violent, and general movement among the various masses of mineral matter which at that time composed its concentric rocky crust; and, as a natural result of this movement, inter se, the evolution by means of friction, of intense heat; and it is when we come to investigate into the origin and direction of these dykes and other mineral protrusions, that more than ever we recognize the soundness of those assumptions. Without movement amongst the stony materials of the earth's original shell there could have been no heat; without heat there would have been neither dykes, veins, nor other overflowings of fused mineral matter. Their mere existence, therefore, testifies to the fact of those fierce heats having been engendered. Whilst the direction they have pursued not only affords evidence to the same effect, but shows that the expanding influence of heat co-operated with the centrifugal force in constraining them to adopt a course somewhat between the two, and towards the surface from every centre of heat, or, what is the same thing, from every mountain range, and thus there was conferred upon them that remarkable coincidence of direction throughout all varieties and inequalities of surface, which no single force could have caused them, under any circumstances whatever, to have pursued.

From what has been said it must appear evident, that any attempt to have explained the origin and direction of these mineral protrusions without reference to centrifugal impetus, would have been as unsuccessful as, on the other hand, any

endeavour to have accounted for them by that force alone, would have been unsatisfactory and inconclusive. Their existence and their geological position are alike due to that inevitable modification of the centrifugal force, occasioned by the heat which that motion engendered. When it raised the heat which melted the mineral matter, it likewise propelled the whole towards the periphery; and both together forced these streams of fused material to find the nearest vent upon the surface, as so many outlets for the extension of the matter which an increase of volume, attendant on that of temperature, had occasioned on the earth's crust; whilst the Creator, by his wisdom and power, made use of all these concomitant circumstances to weld the shattered fragments of the earth's outer crust securely together in the very midst of its convulsions, and to bind stratum to stratum, and rock to rock, in the most perfect and enduring manner by a universal protrusion of veins and dykes, which, after perforating the whole, were clenched and rivetted by their overflowings on the surfacethe mineral bolts and bars of the earth's outer crust! While these veins and dykes afford us yet other undoubted indications. They show us, in the most undeniable manner, whereabouts the surface of the earth then was; for, as long as they had to perforate rocky masses, they proceeded in straight lines, generally speaking, under the combined influence of a superior force, and the opposition which the perforated masses, by their density, offered to their lateral dispersion. But so soon as they reached the surface, or the looser materials of the more recent deposits, having no longer dense substances on each side to confine them, they spread out and around in obedience to the joint laws of gravity and centrifugal impetus ; the latter inducing them to overflow, the other causing the ejected mass to fall down by its own weight: hence we are authorised to conclude, that wherever accumulations of fused rocks are found, the surface either was there at the time of the earth's first rotation, or there were present only materials of less density than the overflowing masses, amongst which they conducted themselves almost as they would have done upon the altogether external surface of the forming continents; while the abrading influence of the primitive ocean, as it simul

taneously rushed from the polar regions towards the equator, to complete the static condition of liquidity under rotation, would greatly contribute to these denuding effects, and leave around these impervious barriers incontestible traces behind it of the path which it hurriedly followed, as it swept past them in its impetuous course.

SECTION VI.

GEOLOGICAL PHENOMENA RESULTING FROM THE EARTH'S

PROTOROTATION.

CHAPTER XXII.

FAULTS or FISSURES described. Geological evidences of their existence. Application of these data to the COAL MEASURES, considered to have been the uppermost strata of the Non-rotatory Sphere. Found to correspond. METALLIC VEINS, described; geological and other scientific data descriptive of these interesting portions of the rocky crust of the earth.

HAVING thus been enabled to indicate the probable origin of the mineral veins which proceed in directions from the centre towards the circumference, we shall in this chapter endeavour to explain, as for as the Dynamical Theory will enable us, whence we consider those called "fissures" or "faults," which proceed in a contrary direction, or from the surface towards the interior of the earth's crust, to have arisen. They are taken notice of in the thirtieth Theorem, and its accompanying evidence, which state, "That two distinct classes of mineral veins are found to exist in the earth's outer crust-one of which proceeds from inwards outwards, having their bases in the interior, and their apici nearest to the surface; and the other termed Faults and Fissures proceeding from outwards inwards, with their apici in the interior and their bases on or near to the surface."

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"In our last chapter," says Professor Buckland, we considered the advantages of the disposition of the carboniferous strata in the form of basins. It remains to examine the further advantages that arise from other disturbances of these strata by faults or fractures, which are of great importance in facilitating the operations of coal