Town Geology

product well known, happily, to all dwellers in towns, and of late years, tha

ht to say at first starting, "Coal is utterly different in look from leaves and stems. The only property which they seem to have in common is that they can both burn." True. But difference of mere look may be only owing to a transformation, or series of transformations. There are plenty in nature quite as great, and greater. What can be more different in look, for instance, than a green field of wh

, baked. We see, in the case of bread, the processes of the transformation going on: but in the case

the moon, who certainly can know nothing of either; for as there is neither air nor water round the moon, there can be nothing to grow there, and therefore nothing to cook-and suppose we asked him to study the series from end to end. Do you not think that the man in the moon, if he were half as shrewd as Crofton Croker makes him in his c

hat however different two objects may look in some respects, yet if you can find a regular series of gradations between them, with all shades of likeness, first to one of them a

niloquent. Let me give

ith one head, and also giants with seven heads, and no others, you would have had a right to say, "There are two breeds of giants here, one-headed and seven-headed." But if you had found, as Jack the Giant-Killer (who belongs to the same old cycle of myths) ap

we arrive most surely at a belief in the unity of the hum

n the white man and the Negro, and not only that, but endless gradations between them both and a third type, whose extreme perhaps is the Chinese-endless gradations, I say, showing every conceivable shade of resemblance or difference, till you often cannot say to what type a given individual belongs; and all of them, however different from each other, more like

at, again, into sunken forests, like those to be seen below high-water mark on many coasts of this island. You find gradations between them and beds of lignite, or wood coal; then gradations between lignite and common or bituminous coal; and then gradations between common coal and culm, or anth

ientific men are in the habit of doing, by saying, If th

rted into shapeless coal. It is likely that there will be vegetable fibre still to be seen here

the coal, are so full of plant-remains, that three hundred species were known to

out these plants of the coal; namely, th

ds there are two noble species, at least, which are true swamp-ferns; the Lastr?a Thelypteris, which of old filled the fens, but is now all but extinct; and the Osmunda, or King-fern, which, as all know, will grow wherever it is damp enough about the roots. In Hampshire, in Devon, and Cornwall, and in the southwest of Ireland, the King-fern too is a true swamp fern. But in the Tropics I have seen more than once noble tree-ferns gro

over most parts of the globe, dwindled down now from twenty or thirty feet in height, as they were in the old coal measures, to paltry little weeds. The talle

ually made up of millions of the minute seeds of club-mosses, such as grow-a few of them, and those very small-on our moors; a proof, surely, not only of the vast amount of the vegetation in the coal-making age, but also of the vast time during which it lasted. The Lepidodendra

e not agreed as to what low order of flowerless plants they belong. But

ch furnishes in some coal-measures bushels of a seed connected with that of the yew-we may suppose that they would find no more difficu

ally wish to know what sort of a world it was in whi

he world in which we are living now, with the one e

: and really there is no need to remember; for it is all, I verily believe, a dream-an attempt to explain the unknown not by the known, but by the still more unknown. You may find such theories lingering still in sensational school-books, if you like to be unscientific. If you like, on the other hand, to be scientific you will listen to those who tell you that instead of there having been one unique carboniferous epoch, with a peculiar coal-making cli

ell's great geological rule-that the best way to explain what we see in ancient rocks is to take for gr

in the north of Wales. Coal probably exists over vast sheets of England and France, buried so deeply under later rocks, that it cannot be reached by mining. As an instance, a distinguished geologist has long held that there are beds of coal under London itself, which rise, owing to a peculiar disturbance of the strata, to within 1,000 or 1,200 feet of the surface, and that we or our children may

the known to the unknown. It was clear that these plants had grown on land; for they were land-plants. It was clear that there must have been land close by, for between t

And it was known that at the mouths of certain rivers-the Mississippi, for instance-vast rafts of dead floating trees accumulated; and that the bottoms o

while when found in the sandstones or shales, they had lost their filaments, and seemed more or less rolled-in fact, that the natural place of the Stigmaria was in the under clay. Then Mr. Binney discovered a tree-a Sigillaria, standing upright in the coal-measures with its roots attached. Those roots penetrated into the under clay of the coal; and those roots were Stigmarias. That seems to have settled the question. The Sigillarias, at least, had grown where they were found, and the clay beneath the coal-beds was the original soil on which they had grown. Just so, if you will look at any peat bog you will find it bottomed by clay, which clay is pierced everywhere by the ro

pretty a specimen as I can give my readers of that regular and gradual induc

rom the decay of trees and semi-aquatic plants; so that when, in a very dry season, the swamp is set on fire, pits are burnt into the ground many feet deep, or as far as the fire can go down without reaching water, and scarcely any earthy residuum is left; just as when the soil of the English fens catches fire, red-hot holes are eaten down through pure peat till the water-bearing clay below is reached. But the purity of the water in peaty lagoons is observable elsewhere than in the delta of the Mississippi. What can be more transparent than many a pool surrounded by quaking bogs, fringed, as they are in Ireland, with

s be true, how were the forests covered up

ng of the land,

ed; and the mud and sand which were brought down the streams enveloped their trunks? As for the inside being full of sandstone, have we not all seen hollow trees? Do we not all know that when a tree dies its wood decays first, its bark last? It is so, especially in the Tropics. There one may see huge dead trees with their bark seemingly sound, and their inside a mere ca

e would be formed, which might do to the collier of the future what they are too apt to do now in the Newcastle and Bristol collieries. For there, when the coal is worked out below, the sandstone stems-"coal-pipes

ir trunks broken off and lying in every direction, turned into coal, and flattened, as coal-fossils so often are, by the weight of the rock above-should we not have a right to say-These trees were

coal-seam, each with its bed of under-clay; and that therefore the land must have sunk

if any reader shall say, Subsidence? What is this quite new element which you have brought into your argument? You told us that you would reason from the known to the unknown. What do we know of subsidence? You offered to explain the thing which had gone on once

land are common now, probably just as common a

in some places to a depth of eighteen feet, and converted it into an inland sea. The same shock raised, a few miles off, a corresponding sheet of land some fifty miles in length, and in some parts sixteen

and thirty miles in breadth, and throughout it, as late as 1846, "dead trees were conspicuous, some erect in the water, others fallen, and strewed in dense masses over the bottom, in the shallows, and near the shore." I quote these words from Sir Charles Lyell's "Principles of Geology" (11th edit.), vol. i. p. 453. And I cannot do better than advise my readers, if they wish to know more of

aking, or getting ready to be made, before my eyes: a sheet of swamp, sinking slowly into the sea; for there stood trees, still rooted below high-water mark, and killed by the waves; while inland huge trees stood dying, or dead, from the water at their roots. But what a scene-a labyrinth of narrow creeks, so narrow that a canoe could not pass up, haunted with alligators and boa-constrictors, parrots and white herons, amid an inextricable confusion of vegetable mud, roots of the alder-like mangroves, and tangled creepers hanging from tree to tree; and overhead huge fan-palms, delighting in the moisture, mingled with still huger broad-leaved trees in every stage of decay. The drowned vegetable soil of ages beneath me; above my head, for a hundred feet, a mass of

ither fallen or upright as they grew, and often mixed with beds of sand or mud, brought down in floods, were formed in exactly the same way; and if they had remained undrained, then that slow sinking, which geologists say is going on over the whole area of the Fens, would have brought them gradually, but surely, below the sea-level, to be covered up by new forests, and converted in due time into coal. And future geologi

the Tropics. Moreover, there must have been, it seems to me, a great scarcity of animal-life. Insects are found, beautifully preserved; a few reptiles, too, and land-shells; but very few. And where are the traces of such a swarming life as would be entombed were a tropic forest now sunk; which is found entombed in many parts of our English fens? The only explanation

continent, a tongue of which ran across the centre of England, and into Ireland, dividing the northern and southern coal-fields. But how far to the west and north did that old continent stretch? Did it, as it almost certainly did long ages afterwards, join Greenland and North America with Scotland and Norway? Were the northern fields of Nova Scotia, which are of the same geological a

all for which I have argued is probable, they w

rmed vegetable matter; but can you show us how the transformati

g with its hydrogen, chiefly in the form of carburetted hydrogen-the gas with which we light our streets. That is about as much as the unscientific reader need know. But it is a fresh corroboration of the theory t

hydrogen and olefiant gases. Now the occurrence of that fire-damp in mines proves that changes are still going on in the coal: that it is getting rid of its hydrogen, and so progressing toward the state of anthracite or culm-stone-coal as it is sometimes called. In the Pennsylvanian coal-fields some of

of immense antiquity, graphite-what we miscall black-lead. And, after that, it might go through one transformation more, and that the most startling of all. It would need only perfect purification and crystallisation to become-a diamond; nothing less. W

ook to us more strange, more truly poe

hey made of? Gas and sunbeams; with a small percentage of a

eams. Strang

, that it might distil them into sap, and bud, and leaf, and wood. But it has to take in another element, without which the distillation and the shaping could never have taken place. It had to drink in the sunbeams-that mysterious and complex force which is for ever pouri

told us long ago, in

the Beam lo

e so well that they made the rose-or rather, the rose took the wind and the beam, and

not set free the sunbeams imprisoned in its tissue. The sun-force must stay, shut up age after age, invisible, but strong; working at its own prison-cells; transmuting them, or making them capab

A corner, an atom of it, warms till it reaches the igniting po

eds, the whole lump is seized, atom after atom, with an infectious hunger for that oxygen which it

zes into the free atmosphere, as light and heat once more; returning in a moment i

, as of the heart of man, the old saying s