Proofs of Design in the Effects of Disturbing
Forces on the Strata of the Earth.
IN the proofs of the agency of a wise, and powerful and benevolent Creator, which we have derived from the Animal and Vegetable kingdoms, the evidence has rested chiefly on the prevalence of Adaptations and Contrivances, and of Mechanisms adapted to the production of certain ends, throughout the organic remains of a former world.
An argument of another kind may be founded on the Order, Symmetry, and Constancy, of the Crystalline forms of the unorganized Mineral ingredients of the Earth. But in considering the great geological phenomena which appear in the disposition of the strata, and their various accidents, a third kind of evidence arises from conditions of the earth, which are the result of disturbing forces, that appear to a certain degree to have acted at random and fortuitously.
Elevations and subsidences, inclinations and contortions, fractures and dislocations, are phenomena, which, although at first sight they present only the appearance of disorder and
[540 ORDER AMIDST APPARENT CONFUSION.] confusion, yet when fully understood, demonstrate the existence of Order, and Method, and Design, even in the operations of the most turbulent, among the many mighty physical forces which have affected the terraqueous globe.*
Some of the most important results of the action of these forces have been already noticed in
* "Notwithstanding the appearances of irregularity and confusion in the formation of the crust of our globe, which are presented to the eye in the contemplation of its external features, Geologists have been able in numerous instances to detect, in the arrangement and position of its stratified masses, distinct approximations to geometrical laws. In the phenomena of anticlinal lines, faults, fissures, mineral veins, &c. such laws are easily recognized." Hopkin's Researches in Physical Geology. Trans. Cambridge Phil. Soc. v. G. part l. 1835.
" It scarcely admits of a doubt," says the author of an able article in the Quarterly Review, (Sept. 1826, p. 537,) " that the agents employed in effecting this most perfect and systematic arrangement have been earthquakes, operating with different degrees of violence, and at various intervals of time, during a lapse of ages. The order that now reigns has resulted therefore, from causes which have generally been considered as capable only of defacing and devastating the earth's surface, but which we thus find strong grounds for suspecting were, in the primeval state of the globe, and perhaps still are, instrumental in its perpetual renovation. The effects of these subterranean forces prove that they are governed by general laws, and that these laws have been conceived by consummate wisdom and forethought."
" Sources of apparent derangement in the system appear, when their operation throughout a series of ages is brought into one view, to have produced a great preponderance of good, and to be governed by fixed general laws, conducive, perhaps essential, to the habitable state of the globe." Ibid. p. 539.
[541 UTILITY OF FAULTS AND DISLOCATIONS.] our fourth and fifth chapters; and our first Section, Pl. 1, illustrates their beneficial effect, in eIevating and converting into habitable Lands, strata of various kinds that were formed at the bottom of the ancient Waters; and in diversifying the surface of these lands with Mountains, Plains, and Valleys, of various productive qualities, and variously adapted to the habitation of Man, and the inferior tribes of terrestrial animals.
In our last Chapter 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 mines; and to extend our inquiry into the more general effect of similar Dislocations of other strata, in producing convenient receptacles for many valuable Metallic ores, and in regulating the supplies of Water from the interior of the earth, through the medium of Springs.
I have elsewhere observcd* that the occurrence of Faults and the inclined position in which the strata composing the Coal measures are usually laid out, are facts of the highest importance, as connected with the accessibility of thcir mineral contents. From their inclined
* Inaugural Lectrire, Oxford, 1819.
[542 BENEFICIAL EFFECTS OF UNDULATIONS.]
position, the thin strata of Coal are worked with greater facility than if they had been horizontal; but as this inclination has a tendency to plunge their lower extremities to a depth that would be inaccessible, a series of Faults, or Traps, is interposed, by which the component portions of the same formation are arranged in a series of successive tables, or stages, rising one behind another, and elevated continually upwards towards the surface, from their lowest points of depression. (See Pl. 65. Fig. 3. and Pl. 66. Fig. 2.) A similar effect is often produced by Undulations or contortions of the strata, which give the united advantage of inclined position and of keeping them near the surface. The Basin-shaped structure which so frequently occurs in coal fields, has a tendency to produce the same beneficial consequences. (See Pl. 65. Figs. l. 2. 3.)
But a still more important benefit results from the occurrence of Faults or Fractures,* without which the contents of many deep and rich mines
" Faults," says Mr. Conybeare, " consist of fissures traversing the strata, extending often for several miles, and penetrating to a depth, in very few instances ascertained; they are accompanied by a subsidence of the strata on one side of their line, or (which amounts to the same thing) an elevation of them on the other; so that it appears, that the same force which has rent the rocks thus asunder, has caused one side of the fractured mass to rise, or the other to sink. — The fissures are usually filled by clay." Geology of England and Wales, Part l. 348.
[543 BENEFICIAL EFFECTS OF FAULTS.] would have been inaccessible. (See Pl. 65. Fig. 3. and Pl. 66. Fig. 2.) Had the strata of Shale and Grit, that alternate with the Coal, been conginuously united without fracture, the quantity of water that would have penetrated from the surrounding country, into any considerable excavations that might be made in the porous grit beds, would have overcome all power of machinery that could profitably be applied to the drainage of a mine; whereas by the simple arrangement of a system of Faults, the water is admitted only in such quantities as are within control. Thus the component strata of a Coal field are divided into insulated masses, or sheets of rock, of irregular form and area, not one of which is continuous in the same plane over any very large district; but each is usually separated from its next adjacent mass, by a dam of clay, impenetrable to water, and filling the fissure produced by the fracture which caused the Fault. (See Pl. 66. Fig. 2. and Pl. l. Figs . 1,—1, 7.)
If we suppose a thick sheet of Ice to be broken into fragments of irregular area, and these fragments again united, after receiving a slight degree of irregular inclination to the plane of the original sheet, the reunited fragments of ice will represent the appearance of the component portions of the broken masses, or sheets of Coal measures we are describing. The intervening portions of more recent Ice, by which they are
[344 DRAINAGE OF COAL MINES.] held together, represent the clay and rubbish that fill the Faults, and form the partition walls that insulate these adjacent portions of strata, which were originally formed, like the sheet of Ice, in one continuous plane. Thus, each sheet or inclined table of Coal measures, is inclosed by a system of more or less vertical walls of broken clay, derived from its argillaceous shale beds, at the moment in which the Fracture and Dislocation took place; and hence have resulted those joints and separations, which, though they occasionally interrupt at inconvenient positions, and cut off suddenly the progress of the collier, and often shatter those portions of the strata that are in immediate contact with them, yet are in the main his greatest safeguard, and are indeed essential to his operations.*
These same Faults also, whilst they prevent the Water from flowing in excessive quantities in
" If a field of coal (says Mr. Buddle) abounding in water, was not intersected with slip Dykes, the working of it might be impracticable, as the whole body of water which it might contain would flow uninterruptedly into any opening which might be made into it; these Faults operate as Coffer Dams, and separate the field of coal into districts." — Letter from Mr. John Buddle, an eminent Engineer and experienced Coal Viewer at Newcastle, to Prof. Buckland, Nov. 30, 1831.
In working a Coal Pit, the Miner studiously avoids coming near a Fault, knowing that if he should penetrate this natural barrier, the Water from the other side will often burst in, and inundate the works he is conducting on the dry side of it.
A shaft was begun about the year 1825 at Gosforth, near
[545 FAULTS PRODUCE SPRINGS.] situations where it would be detrimental, are at the same time of the greatest service, in converting it to purposes of utility, by creating on the surface a series of Springs along the line of Fault, which often give notice of the Fracture that has taken place beneath. This important effect of Faults on the hydraulic machinery of the globe extends through stratified rocks of every formation. (See Pl. 69. Fig. 2.) It is also probable that most of the Springs, that issue from unstratified rocks, are kept in action through the instrumentality of the Faults by which they are intersected.
A similar interruption of continuity in the masses of Primary rocks, and in the rocks of intermediate age between these and the Coal formation, is found to occur extensively in the working of metallic veins. A vein is often cut off suddenly by a Fault, or fracture, crossing it
Newcastle, on the wet side of the 90 fathom Dyke,
inundated with water that it was soon found necessary to abandon
it. Another shaft was then begun on the dry side of the dyke, only a few yards from the former, and in this they descended nearly 200 fathoms without any impediment from water.
Artificial dams are sometimes made in coal mines to perform the office of the natural barriers which Dykes and Faults upply. A dam of this kind was lately made near Manchester, by Mr. Hulton, to cut off water that descended from the upper regions of porous strata, which dipped towards his excavations in a lower region of the same strata, the continuity of which was thus artificially interrupted.
[546 FAULTS INTERSECT METALLIC VEINS.] transversely, and its once continuous portions are thrown to a considerable distance from each other. This line of fracture is usually marked by a wall of clay, formed probably by the abrasion of the rocks whose adjacent portions have been thus dislocated. Such faults are known in the mines of Cornwall by the term flucan, and they often produce a similar advantage to those that traverse the Coal measures, in guarding the miner from inundation, by a series of natural dams traversing the rocks in various directions, and intercepting all communication between that mass in which he is conducting his operations, and the adjacent masses on the other side of the flucan or dam.*
It may be added also, that the Faults in a Coal field, by interrupting the continuity of the beds of coal, and causing their truncated edges to abut against those of uninflammable strata of shale or
" My object is rather to suggest whether the arrangement of veins, &c. does not argue design and a probable connection with other phenomena of our Globe.
" Metalliferous veins, and those of quartz, &c. appear to be channels for the circulation of the subterraneous water and vapour; and the innumerable clay veins, or "flucan courses (as they are termed in Cornwall), which intersect them, and are often found contained in them, being generally impervious to water, prevent their draining the surface of the higher grounds as they otherwise would, and also facilitate the working of mines to a much greater depth than would be practicable without them." R. W. Fox on the Mines of Cornwall, Phil. Trans. 1830, p. 404.
[547 FINAL CAUSES.] grit, afford a preservative against the ravages of accidental Fire beyond the area of that sheet in which it may take its beginning; but for such a provisions entire Coal fields might be occasionally burnt out and destroyed.
It is impossible to contemplate a disposition of things, so well
to afford the materials essential to supply the first wants, and to
alive the industry of the Inhabitants of our earth; and entirely to
such a disposition to the blind operation of Fortuitous causes.
Although indeed it be dangerous hastily to have recourse to Final causes,
yet since in many branches of physical knowledge, (more especially in
which relate to organized matter,) the end of many a contrivance is
understood, than the contrivance itself, it would surely be as
to hesitate at the admission of final Causes, when the general tenor
evidence of the Phenomena naturally suggest them, as it would be to
them gratuitously unsupported by such evidence. We may surely therefore
feel ourselves authorized to view, in the Geological arrangements above
described, a System of wise and benevolent Contrivances, prospectively
subsidiary to the wants and comforts of the future inhabitants of the
and extending onwards, from its first Formation, through the subsequent
Revolutions and Convulsions that have affected the surface of our