Town Geology

I appeal to your common sense.  If He who spoke these words were (as I believe) none other than the Creator of the universe, by whom all things were made, and without whom nothing was made that is made, do you suppose that He would have bid you to consider His universe, had it been dangerous for you to do so?

Do you suppose, moreover, that the universe, which He, the Truth, the Light, the Love, has made, can be otherwise then infinitely worthy to be considered? or that the careful, accurate, and patient consideration of it, even to its minutest details, can be otherwise than useful to man, and can bear witness of aught, save the mind and character of Him who made it?  And if so, can it be a work unfit for, unworthy of, a clergyman—whose duty is to preach Him to all, and in all ways,—to call on men to consider that physical world which, like the spiritual world, consists, holds together, by Him, and lives and moves and has its being in Him?

And here I must pause to answer an objection which I have heard in my youth from many pious and virtuous people—better people in God’s sight, than I, I fear, can pretend to be.

They used to say, “This would be all very true if there were not a curse upon the earth.”  And then they seemed to deduce, from the fact of that curse, a vague notion (for it was little more) that this world was the devil’s world, and that therefore physical facts could not be trusted, because they were disordered, and deceptive, and what not.

Now, in justice to the Bible, and in justice to the Church of England, I am bound to say that such a statement, or anything like it, is contrary to the doctrines of both.  It is contrary to Scripture.  According to it, the earth is not cursed.  For it is said in Gen. viii. 21, “And the Lord said, I will not again curse the ground any more for man’s sake.  While the earth remaineth, seed-time and harvest, cold and heat, summer and winter, day and night shall not cease.”  According to Scripture, again, physical facts are not disordered.  The Psalmist says, “They continue this day according to their ordinance; for all things serve Thee.”  And again, “Thou hast made them fast for ever and ever.  Thou hast given them a law which cannot be broken.”

So does the Bible (not to quote over again the passages which I have already given you from St. Paul, and One greater than St. Paul) declare the permanence of natural laws, and the trustworthiness of natural phenomena as obedient to God.  And so does the Church of England.  For she has incorporated into her services that magnificent hymn, which our forefathers called the Song of the Three Children; which is, as it were, the very flower and crown of the Old Testament; the summing up of all that is true and eternal in the old Jewish faith; as true for us as for them: as true millions of years hence as it is now—which cries to all heaven and earth, from the skies above our heads to the green herb beneath our feet, “O all ye works of the Lord, bless ye the Lord; praise Him and magnify Him for ever.”  On that one hymn I take my stand.  That is my charter as a student of Natural Science.  As long as that is sung in an English church, I have a right to investigate Nature boldly without stint or stay, and to call on all who have the will, to investigate her boldly likewise, and with Socrates of old, to follow the Logos whithersoever it leads.

The Logos.  I must pause on that word.  It meant at first, no doubt, simply speech, argument, reason.  In the mind of Socrates it had a deeper meaning, at which he only dimly guessed; which was seen more clearly by Philo and the Alexandrian Jews; which was revealed in all its fulness to the beloved Apostle St. John, till he gathered speech to tell men of a Logos, a Word, who was in the beginning with God, and was God; by whom all things were made, and without Him was not anything made that was made; and how in Him was Life, and the Life was the light of men; and that He was none other than Jesus Christ our Lord.

Yes, that is the truth.  And to that truth no man can add, and from it no man can take away.  And as long as we believe that as long as we believe that in His light alone can we see light—as long as we believe that the light around us, whether physical or spiritual, is given by Him without whom nothing is made—so long we shall not fear to meet Light, so long we shall not fear to investigate Life; for we shall know, however strange or novel, beautiful or awful, the discoveries we make may be, we are only following the Word whithersoever He may lead us; and that He can never lead us amiss

I. THE SOIL OF THE FIELD[2 - These Lectures were delivered to the members of the Natural Science Class at Chester in 1871.]

My dear readers, let me, before touching on the special subject of this paper, say a few words on that of the whole series.

It is geology: that is, the science which explains to us the rind of the earth; of what it is made; how it has been made.  It tells us nothing of the mass of the earth.  That is, properly speaking, an astronomical question.  If I may be allowed to liken this earth to a fruit, then astronomy will tell us—when it knows—how the fruit grew, and what is inside the fruit.  Geology can only tell us at most how its rind, its outer covering, grew, and of what it is composed; a very small part, doubtless, of all that is to be known about this planet.

But as it happens, the mere rind of this earth-fruit which has, countless ages since, dropped, as it were, from the Bosom of God, the Eternal Fount of Life—the mere rind of this earth-fruit, I say, is so beautiful and so complex, that it is well worth our awful and reverent study.  It has been well said, indeed, that the history of it, which we call geology, would be a magnificent epic poem, were there only any human interest in it; did it deal with creatures more like ourselves than stones, and bones, and the dead relics of plants and beasts.  Whether there be no human interest in geology; whether man did not exist on the earth during ages which have seen enormous geological changes, is becoming more and more an open question.

But meanwhile all must agree that there is matter enough for interest—nay, room enough for the free use of the imagination, in a science which tells of the growth and decay of whole mountain-ranges, continents, oceans, whole tribes and worlds of plants and animals.

And yet it is not so much for the vastness and grandeur of those scenes of the distant past, to which the science of geology introduces us, that I value it as a study, and wish earnestly to awaken you to its beauty and importance.  It is because it is the science from which you will learn most easily a sound scientific habit of thought.  I say most easily; and for these reasons.  The most important facts of geology do not require, to discover them, any knowledge of mathematics or of chemical analysis; they may be studied in every bank, every grot, every quarry, every railway-cutting, by anyone who has eyes and common sense, and who chooses to copy the late illustrious Hugh Miller, who made himself a great geologist out of a poor stonemason.  Next, its most important theories are not, or need not be, wrapped up in obscure Latin and Greek terms.  They may be expressed in the simplest English, because they are discovered by simple common sense.  And thus geology is (or ought to be), in popular parlance, the people’s science—the science by studying which, the man ignorant of Latin, Greek, mathematics, scientific chemistry, can yet become—as far as his brain enables him—a truly scientific man.

But how shall we learn science by mere common sense?

First.  Always try to explain the unknown by the known.  If you meet something which you have not seen before, then think of the thing most like it which you have seen before; and try if that which you know explains the one will not explain the other also.  Sometimes it will; sometimes it will not.  But if it will, no one has a right to ask you to try any other explanation.

Suppose, for instance, that you found a dead bird on the top of a cathedral tower, and were asked how you thought it had got there.  You would say, “Of course, it died up here.”  But if a friend said, “Not so; it dropped from a balloon, or from the clouds;” and told you the prettiest tale of how the bird came to so strange an end, you would answer, “No, no; I must reason from what I know.  I know that birds haunt the cathedral tower; I know that birds die; and therefore, let your story be as pretty as it may, my common sense bids me take the simplest explanation, and say—it died here.”  In saying that, you would be talking scientifically.  You would have made a fair and sufficient induction (as it is called) from the facts about birds’ habits and birds’ deaths which you know.

But suppose that when you took the bird up you found that it was neither a jackdaw, nor a sparrow nor a swallow, as you expected, but a humming-bird.  Then you would be adrift again.  The fact of it being a humming-bird would be a new fact which you had not taken into account, and for which your old explanation was not sufficient; and you would have to try a new induction—to use your common sense afresh—saying, “I have not to explain merely how a dead bird got here, but how a dead humming-bird.”

And now, if your imaginative friend chimed in triumphantly with: “Do you not see that I was right after all?  Do you not see that it fell from the clouds? that it was swept away hither, all the way from South America, by some south-westerly storm, and wearied out at last, dropped here to find rest, as in a sacred-place?” what would you answer?  “My friend, that is a beautiful imagination; but I must treat it only as such, as long as I can explain the mystery more simply by facts which I do know.  I do not know that humming-birds can be blown across the Atlantic alive.  I do know they are actually brought across the Atlantic dead; are stuck in ladies’ hats.  I know that ladies visit the cathedral; and odd as the accident is, I prefer to believe, till I get a better explanation, that the humming-bird has simply dropped out of a lady’s hat.”  There, again, you would be speaking common sense; and using, too, sound inductive method; trying to explain what you do not know from what you do know already.

Now, I ask of you to employ the same common sense when you read and think of Geology.

It is very necessary to do so.  For in past times men have tried to explain the making of the world around them, its oceans, rivers, mountains, and continents, by I know not what of fancied cataclysms and convulsions of nature; explaining the unknown by the still more unknown, till some of their geological theories were no more rational, because no more founded on known facts, than that of the New Zealand Maories, who hold that some god, when fishing, fished up their islands out of the bottom of the ocean.  But a sounder and wiser school of geologists now reigns; the father of whom, in England at least, is the venerable Sir Charles Lyell.  He was almost the first of Englishmen who taught us to see—what common sense tells us—that the laws which we see at work around us now have been most probably at work since the creation of the world; and that whatever changes may seem to have taken place in past ages, and in ancient rocks, should be explained, if possible, by the changes which are taking place now in the most recent deposits—in the soil of the field.

And in the last forty years—since that great and sound idea has become rooted in the minds of students, and especially of English students, geology has thriven and developed, perhaps more than any other science; and has led men on to discoveries far more really astonishing and awful than all fancied convulsions and cataclysms.

I have planned this series of papers, therefore, on Sir Charles Lyell’s method.  I have begun by trying to teach a little about the part of the earth’s crust which lies nearest us, which we see most often; namely, the soil; intending, if my readers do me the honour to read the papers which follow, to lead them downward, as it were, into the earth; deeper and deeper in each paper, to rocks and minerals which are probably less known to them than the soil in the fields.  Thus you will find I shall lead you, or try to lead you on, throughout the series, from the known to the unknown, and show you how to explain the latter by the former.  Sir Charles Lyell has, I see, in the new edition of his “Student’s Elements of Geology,” begun his book with the uppermost, that is, newest, strata, or layers; and has gone regularly downwards in the course of the book to the lowest or earliest strata; and I shall follow his plan.

I must ask you meanwhile to remember one law or rule, which seems to me founded on common sense; namely, that the uppermost strata are really almost always the newest; that when two or more layers, whether of rock or earth—or indeed two stones in the street, or two sheets on a bed, or two books on a table—any two or more lifeless things, in fact, lie one on the other, then the lower one was most probably put there first, and the upper one laid down on the lower.  Does that seem to you a truism?  Do I seem almost impertinent in asking you to remember it?  So much the better.  I shall be saved unnecessary trouble hereafter.

But some one may say, and will have a right to say, “Stop—the lower thing may have been thrust under the upper one.”  Quite true: and therefore I said only that the lower one was most probably put there first.  And I said “most probably,” because it is most probable that in nature we should find things done by the method which costs least force, just as you do them.  I will warrant that when you want to hide a thing, you lay something down on it ten times for once that you thrust it under something else.  You may say, “What?  When I want to hide a paper, say, under the sofa-cover, do I not thrust it under?”

No, you lift up the cover, and slip the paper in, and let the cover fall on it again.  And so, even in that case, the paper has got into its place first.

Now why is this?  Simply because in laying one thing on another you only move weight.  In thrusting one thing under another, you have not only to move weight, but to overcome friction.  That is why you do it, though you are hardly aware of it: simply because so you employ less force, and take less trouble.

And so do clays and sands and stones.  They are laid down on each other, and not thrust under each other, because thus less force is expended in getting them into place.

There are exceptions.  There are cases in which nature does try to thrust one rock under another.  But to do that she requires a force so enormous, compared with what is employed in laying one rock on another, that (so to speak) she continually fails; and instead of producing a volcanic eruption, produces only an earthquake.  Of that I may speak hereafter, and may tell you, in good time, how to distinguish rocks which have been thrust in from beneath, from rocks which have been laid down from above, as every rock between London and Birmingham or Exeter has been laid down.  That I only assert now.  But I do not wish you to take it on trust from me.  I wish to prove it to you as I go on, or to do what is far better for you: to put you in the way of proving it for yourself, by using your common sense.

At the risk of seeming prolix, I must say a few more words on this matter.  I have special reasons for it.  Until I can get you to “let your thoughts play freely” round this question of the superposition of soils and rocks, there will be no use in my going on with these papers.

Suppose then (to argue from the known to the unknown) that you were watching men cleaning out a pond.  Atop, perhaps, they would come to a layer of soft mud, and under that to a layer of sand.  Would not common sense tell you that the sand was there first, and that the water had laid down the mud on the top of it?  Then, perhaps, they might come to a layer of dead leaves.  Would not common sense tell you that the leaves were there before the sand above them?  Then, perhaps, to a layer of mud again.  Would not common sense tell you that the mud was there before the leaves?  And so on down to the bottom of the pond, where, lastly, I think common sense would tell you that the bottom of the pond was there already, before all the layers which were laid down on it.  Is not that simple common sense?

Then apply that reasoning to the soils and rocks in any spot on earth.  If you made a deep boring, and found, as you would in many parts of this kingdom, that the boring, after passing through the soil of the field, entered clays or loose sands, you would say the clays were there before the soil.  If it then went down into sandstone, you would say—would you not?—that sandstone must have been here before the clay; and however thick—even thousands of feet—it might be, that would make no difference to your judgment.  If next the boring came into quite different rocks; into a different sort of sandstone and shales, and among them beds of coal, would you not say—These coal-beds must have been here before the sandstones?  And if you found in those coal-beds dead leaves and stems of plants, would you not say—Those plants must have been laid down here before the layers above them, just as the dead leaves in the pond were?

If you then came to a layer of limestone, would you not say the same?  And if you found that limestone full of shells and corals, dead, but many of them quite perfect, some of the corals plainly in the very place in which they grew, would you not say—These creatures must have lived down here before the coal was laid on top of them?  And if, lastly, below the limestone you came to a bottom rock quite different again, would you not say—The bottom rock must have been here before the rocks on the top of it?

And if that bottom rock rose up a few miles off, two thousand feet, or any other height, into hills, what would you say then?  Would you say: “Oh, but the rock is not bottom rock; is not under the limestone here, but higher than it.  So perhaps in this part it has made a shift, and the highlands are younger than the lowlands; for see, they rise so much higher?”  Would not that be as wise as to say that the bottom of the pond was not there before the pond mud, because the banks round the pond rose higher than the mud?

Now for the soil of the field.

If we can understand a little about it, what it is made of, and how it got there, we shall perhaps be on the right road toward understanding what all England—and, indeed, the crust of this whole planet—is made of; and how its rocks and soils got there.

But we shall best understand how the soil in the field was made, by reasoning, as I have said, from the known to the unknown.  What do I mean?  This: On the uplands are fields in which the soil is already made.  You do not know how?  Then look for a field in which the soil is still being made.  There are plenty in every lowland.  Learn how it is being made there; apply the knowledge which you learn from them to the upland fields which are already made.

If there is, as there usually is, a river-meadow, or still better, an æstuary, near your town, you have every advantage for seeing soil made.  Thousands of square feet of fresh-made soil spread between your town and the sea; thousands more are in process of being made.

You will see now why I have begun with the soil in the field; because it is the uppermost, and therefore latest, of all the layers; and also for this reason, that, if Sir Charles Lyell’s theory be true—as it is—then the soils and rocks below the soil of the field may have been made in the very same way in which the soil of the field is made.  If so, it is well worth our while to examine it.

You all know from whence the soil comes which has filled up, in the course of ages, the great æstuaries below London, Stirling, Chester, or Cambridge.

It is river mud and sand.  The river, helped by tributary brooks right and left, has brought down from the inland that enormous mass.  You know that.  You know that every flood and freshet brings a fresh load, either of fine mud or of fine sand, or possibly some of it peaty matter out of distant hills.  Here is one indisputable fact from which to start.  Let us look for another.