CHAPTER I.
Extent of the Province of Geology.
IF a stranger, landing at the extremity of England, were to traverse the whole of Cornwall and the North of Devonshire; and crossing to St. David's, should make the tour of all North Wales; and passing thence through Cumberland, by the Isle of Man, to the south-western shore of Scotland, should proceed either through the hilly region of the Border Counties, or, along the Grampians, to the German Ocean; he would conclude from such a journey of many hundred miles, that Britain was a thinly peopled sterile region, whose principal inhabitants were miners and mountaineers.
Another foreigner, arriving on the coast of Devon, and crossing the Midland Counties, from the mouth of the Exe, to that of the Tyne, would find a continued succession of
[002] hills and valleys, thickly overspread with towns and cities, and in many parts crowded with a manufacturing population, whose industry is maintained by the coal with which the strata of these districts are abundantly interspersed.*
A third foreigner might travel from the coast of Dorset to the coast of Yorkshire, over elevated plains of oolitic limestone, or of chalk; without a single mountain, or mine, or coal-pit, or any important manufactory, and occupied by a population almost exclusively agricultural.
Let us suppose these three strangers to meet at the termination of their journeys, and to compare their respective observations; how different would be the results to which each would have arrived, respecting the actual condition of Great Britain. The first would represent it as a thinly peopled region of barren mountains; the second, as a land of rich pastures, crowded with
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It may be seen, in any correct geological map of England, that the following important and populous towns are placed upon strata belonging to the single geological formation of the new red sandstone : — Exeter, Bristol, Worcester, Warwick, Birmingham, Lichfield, Coventry, Leicester, Nottingham, Derby, Stafford, Shrewsbury, Chester, Liverpool, Warrington, Manchester, Preston, York, and Carlisle. The population of these nineteen towns, by the census of 1830, exceeded a million.
The most convenient small map to which I can refer my readers, in illustration of this and other parts of the present essay, is the single sheet, reduced by Gardner from Mr. Greenough's large map of England, published by the Geological Society of London.
[003] a flourishing population of manufacturers; the third, as a
great
corn field, occupied by persons almost exclusively engaged in the
pursuits
of husbandry.
These dissimilar conditions of three great divisions of our country,
result from differences in the geological structure of the districts
through
which our three travellers have been conducted. The first will have
seen
only those north-western portions of Britain, that are composed, of
rocks
belonging to the primary and transition series: the second will have
traversed
those fertile portions of the new red sandstone formation which are
made
up of the detritus of more ancient rocks, and have beneath, and near
them,
inestimable treasures of mineral coal:
the third will have confined his route to wolds of limestone, and downs
of chalk, which are best adapted for sheep-walks, and the production of
corn.*
Hence it appears that the numerical amount
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* The road from Bath through Cirencester and Oxford
to
Buckingham, and thence by Kettering and Stamford to
Lincoln,
affords a good example of the unvaried sameness in the features and
culture
of the soil, and in the occupations of the people, that attends the
line
of direction, in which the oolite formation crosses England from
Weymouth
to Scarborough.
The road from Dorchester, by Blandford and Salisbury,
to Andover and Basingstoke, or from Dunstable to Royston, Cambridge,
and
Newmarket, affords similar examples of the dull uniformity that we
observe
in a journey along the line of bearing of the chalk, from near Bridport
on the coast of Dorset, to Flamborough Head on the coast of Yorkshire.
In the same line of direction, or line of bearing of the strata across England, a journey might be made from Lyme Regis to Whitby, almost entirely upon the lias formation; and from Weymouth to the Humber, without once leaving the Oxford clay. Indeed almost any route, taking a north-east and south-west direction across England, will for the most part pass continuously along the same formation; whilst a line from south-east to north-west, at right angles to the former, will nowhere continue on the same stratum beyond a few miles. Such a line will give the best information of the order of superposition, and various conditions of the very numerous strata, that traverse our island in a succession of narrow belts, the main direction of which is nearly north-east and south-west. This line has afforded to Mr. Conybeare the instructive section, from Newhaven near Brighton, to Whitehaven, published in his Geology of England and Wales; along which nearly seventy changes in the character of the strata take place.
[004] of our population, their varied occupations, and the fundamental sources of their industry and wealth, depend, in a great degree, upon the geological character of the strata on which they live. Their physical condition also, as indicated by the duration of life and health, depending on the more or less salubrious nature of their employments; and their moral condition, as far as it is connected with these employments, are directly affected by the geological causes in which their various occupations originate.
From this example of our own country, we learn that the same constituent materials of the
[005] earth are not uniformly continuous in all directions over large superficial areas. In one district, we trace the course of crystalline and granitic rocks; in another, we find mountains of slate; in a third, alternating strata of sandstone, shale, and limestone; in a fourth, beds of conglomerate rock; in a fifth, strata of marl and clay; in a sixth, gravel, loose sand, and silt. The subordinate mineral contents of these various formations are also different; in the more ancient, are veins of gold and silver, tin, copper, lead and zinc; in another series, we find beds of coal; in others, salt and gypsum; many are composed of freestone, fit for the purposes of architecture; or of limestone, useful both for building and cement; others of clay, convertible by fire into materials for building, and pottery: in almost all we find that most important of mineral productions, iron.
Again, if we look to the great phenomena of physical geography, the grand distributions of the solids and fluids of the globe, the disposition of continents and islands above and amidst the waters; the depth and extent of seas, and lakes, and rivers; the elevation of hills and mountains; the extension of plains; and the excavation, de pression, and fractures of valleys; we find them all originating in causes which it is the province of Geology to investigate.
A more minute examination traces the progress
[006] of the mineral materials of the earth, through various stages of change and revolution, affecting the strata which compose its surface; and discloses a regular order in the superposition of these strata; recurring at distant intervals, and accompanied by a corresponding regularity in the order of succession of many extinct races of animals and vegetables, that have followed one after another during the progress of these mineral formations; arrangements like these could not have originated in chance, since they afford evidence of law and method in the disposition of mineral matter; and still stronger evidence of design in the structure of the organic remains with which the strata are interspersed.
How then has it happened that a science thus important, comprehending no less than the entire physical history of our planet, and whose documents are co-extensive with the globe, should have been so little regarded, and almost without a name, until the commencement of the present century?
Attempts have been made at various periods, both by practical
observers
and by ingenious speculators, to establish theories respecting the
formation
of the earth; these have in great part failed, in consequence of the
then
imperfect state of those subsidiary sciences, which, within the last
half
century, have enabled the geologist to return from the region of fancy
to that of
[007] facts, and to establish his conclusions on the firm basis of
philosophical
induction. We now approach the study of the natural history of the
globe,
aided not only by the higher branches of Physics, but by still more
essential
recent discoveries, in Mineralogy, and Chemistry, in Botany, Zoology,
and
Comparative Anatomy. By the help of these sciences, we are en abled to
extract from the archives of the interior of the earth, intelligible
records
of former conditions of our planet, and to decipher documents, which
were
a sealed book to all our predecessors in the attempt to illustrate
subterranean
history. Thus enlarged in its views, and provided with fit means of
pursuing
them, Geology extends its researches into regions more vast and remote,
than come within the scope of any other physical science except
Astronomy.
It not only comprehends the entire range of the mineral kingdom, but
includes
also the history of innumerable extinct races of animals and
vegetables;
in each of which it exhibits evidences of design and contrivance, and
of
adaptations to the varying condition of the lands and waters on which
they
were placed; and besides all these, it discloses an ulterior
prospective
accommodation of the mineral elements, to existing tribes of plants and
animals, and more especially to the uses of man. Evidences like these
make
up a history of a high
[008 CONSISTENCY OF GEOLOGICAL] and ancient order, unfolding records
of the operations of the Almighty Author of the Universe, written by
the
finger of God himself, upon the foundations of the everlasting hills.