The Floor of the Deep Oceans: What Are They Like

[00:00:00] CHAIRMAN:
The story goes that in December of nineteen seventy-three, when Brian Josephson was rehearsing in Stockholm to get his Nobel Prize, somebody looked at him and realized that he was a little bit too nervous. So trying to calm him down, they mentioned to him, “You shouldn’t be very nervous. It’s all right.

It’s the first time you get a Nobel Prize, but it’s also the first time the king gives a Nobel Prize this year.” Actually, that’s exactly the way I feel. I’m the chairman of the Hitchcock Committee, and it happens to be the first time I’m here to introduce Professor Sir Edward Bullard.

Let me give you a little bit of, uh, introduction. This is a Hitchcock Professorship lecture. The Hitchcock Professorship has been instituted since nineteen oh nine, has a very long tradition at the University of California, and it’s one of the occasions that I think brings joy and exchange of information in this community.

It was endowed by Mr. Charles Hitchcock, and the funds were increased later on by his daughter. And the endowment reads, “For a professorship in the University of California for free lectures upon scientific and practical subjects, but not for the advantage of any religious sect, nor upon political subjects.” Well, I think that, uh, times have changed since these things were written, but I think the spirit is still here.

The other thing I should mention is that this professorship is administered by a committee of the faculty, so we are fully responsible for everything that goes on here. We select our speakers, we invite them, and we are responsible for trying to get them here and try to get the best people to, uh, give us the best possible lectures. Fortunately, I have to say that I have no saying whatsoever in who was invited tonight.

It was given to me by the previous committee. I am very proud to be able to introduce Sir Edward Bullard. Now let’s go to the speaker tonight.

Sir Edward Bullard was born in 1907, and he received his education in Cambridge all along. He’s a fellow of Churchill College. He got his PhD in nineteen thirty-one, and that year he tried to get a job in physics.

His PhD was in physics. There were no jobs available in physics. He got a demonstratorship in geography, and under the advice of Lord Rutherford, he took it.

I think it was very good for everybody. After that, the Second World War came, and Sir Edward Bullard served in the Royal Navy, and he went back to Cambridge at that point. Then he served for two years, nineteen forty-eight, forty-nine at the University of Toronto as a professor, and from nineteen fifty to nineteen fifty-five, he was the head of the National Physical Laboratory in Great Britain.

He returned to Cambridge in nineteen fifty-six. He was elected to the Royal Society of London in nineteen forty-one. Was knighted in nineteen forty-three– in nineteen fifty-three.

Was a foreign associate of the National Academy of Science now, and he has received the Day Medal of the Geo, uh, Geological Society of America in nineteen fifty-nine. His line of research has been in geophysics, and he has made very important contributions in very many areas. His original research was measurements of the gravity in East Africa.

Since 1960, 1950, his work has been mainly concerned with the origins of the magnetic field, and he has formulated a theory that’s known as the dynamo problem, in which he and his students have collaborated. He’s also very well known for his theory of the origin of the continental drift and the seafor– seafloor spreading. He made a reconstruction of the motion of the continents by geometrical means, and his theory has been quoted practically in every scientific journal throughout the world.

Currently, S-Sir Edward is moving from Cambridge to La Jolla. He has been a professor of physics– of geophysics at the University of California, La Jolla, but taking his uh, appointment only a few months every year, going back to England. Since he has retired now from England, he’s, uh, planning to spend more time here with us in the West Coast.

I am very pleased to introduce Sir Edward Bullard, who is going to talk to us tonight on the floor of the deep oceans. What are they like?

[00:04:44] SIR EDWARD BULLARD:
Thank you.

(applause)

Is this microphone working all right? Yes, I think it is. All is well.

I’ve even got my notes with me. I’m going to talk about the geology of the floor of the deep oceans. Now, the history of geology is rather odd.

Geology existed for about two hundred years and concentrated on studying the one-third of the Earth’s surface that is not covered by water. And I think it’s clear that this was imprudent. Uh, that’s to say that if you have an object and you set out to study it, it’s unwise to confine your attention to one-third of it, because the one-third of it that you study may not be typical, And then you’re really in trouble.

The reasons for this, of course, were fairly obvious. Yes. That the part of the Earth which is dry, uh, the continents, uh, It can be studied fairly easily.

You need a stout pair of shoes and a hammer and other conveniences like microscopes and so on, and you can go out and collect your rocks, and you can look at them and say, “This is folded here, it’s so and so somewhere else.” But when you embark on the ocean, you have very great difficulties. You’ve got to develop a whole technology, and you’ve got to collect enough cash, uh, to get ships and to do the things you want to do.

And the geologists were not really that kind of person. The nineteenth century and even the twentieth century geologists were mostly not really big operators. They–

I remember once talking to a very eminent professor of geology, uh, just before the war, And he said, “You know, Teddy, I wouldn’t know how to borrow a submarine even if I wanted to.” And this was by and large true. And it was really, I think, the experience of the war which led a whole group of physicists who had learnt during the war how to manipulate the environment, how to get– how to work the government machine, uh, how to get grants, um, how to borrow submarines, how to do all the things that were necessary.

It was really this experience which led, um, this slightly Bolshevik group of physicists to invade the subject of geology and to decide to look at the other two-thirds of the earth, which had previously been substantially neglected. I don’t say it had been neglected altogether, but certainly the effort had been really rather small. The thing had started, uh, before the war.

There was a wonderful man called, uh, Dick Field at Princeton who got the very simple idea that I’ve already expressed, that one ought to look at the geology of the oceans. But he was… really behaved rather like an Old Testament prophet. He, um, wouldn’t take no for an answer.

Um, he would chase you round till you did what he wanted. And there’s a story of an admiral, um, who, who said– who picked up his telephone and said, “Give this man what he wants, but get him out of my office.” Well, anyway, the thing had started before the war, but it was e-essentially the experience of the war, uh, that got it going in a big way.

And naturally, we started from the beach where we knew something about the geology and moved out, uh, into the ocean. So the first thing to investigate was the continental shelf. The continental shelf is the relatively shallow water around the continent.

Um, if you don’t mind, I’m not going to talk at first about California. F- the reasons for this will appear later. It’s rather a complicated place.

I would rather talk about almost anywhere else. So let’s say that you set off from New York, and you go out to sea. Well, you’ll find relatively shallow water going from nothing at the beach out to a few hundred feet at the edge of the continental shelf.

And this was the first thing that was investigated. And fortunately, there was the most enormous initial success. It was found, really quite unexpectedly, that the continental shelf, which was clearly part of the continent and not part of the deep ocean, was underlain by a tremendous thickness of sediments, uh, rocks that had been laid down in water.

The– apparently, the basement rocks, the hard rocks had been sinking and sinking and sinking, and were covered with something like two miles of sediments. And of course, this great pile of sediments has turned out to be the primary source of new politically secure oil. At any rate, whatever you may say of the American government, um, at, at least it, it isn’t quite like the Arabs to deal with, um, that you can work the oil around this country without the kind of troubles that you have in the Middle East.

So that what better thing could have happened? Here was the start of the investigation of the geology of the oceans, and straight away, this tremendous discovery of the thick sediments was made. Then very slowly, the oil companies got interested.

I remember the oil companies saying before the war, “Why should we be interested in looking for oil at sea? There’s plenty of oil in the Middle East. Why should we worry about looking for it, um, under the water?”

But of course, by the end of the war, the danger signs were there to see, and they became extremely interested in the matter. And personally, I decided that once they’d got interested, uh, then there was no point in us working there anymore because they would clearly do everything that needed to be done. So most of the academic people moved out into the deeper water, and left the continental shelves to the oil companies.

(laughter)

Um, this is not entirely. There are many academic problems on the continental shelves, but on the whole, you’re rather– it’s rather an unfair competition competing with an oil company which is desperately interested in all the details. Well, the first slide, um, shows this state of affairs.

Now I wonder how this works. Um, here is, here is the beach. This is the continent, here is the beach, and here is the shallow water over the shelf, and here are the thick sediments shown in a rather, uh, dia-diagrammatic, um, picture.

And this is, this is where all the continental shelf oil is. Here is the water of, of the deep, of the deep ocean. And the crust of the Earth is much thicker under the continents, uh, than it is under the oceans.

These… Oh, here is a more realistic picture. This is a piece of the continental shelf off Gabon in Africa, and shows the relatively complicated things.

There’s a, a, a lot of salt here which has been pushed up into these salt domes, and you get oil, oil around those This is a rather more realistic picture. The other one was a diagram. This is based in detail on the oil company’s results.

And here is the real edge of the continent with the continental rocks here, the hard basement rocks here, and the sediments on top, and these are the oceanic rocks. Well, then you come out into the d– into the deep ocean. As you, as you go out to sea, if you’re going out from England, you come along the Channel, go out over this continental shelf, and very suddenly you get to an edge.

And in a minute or so, the echo sounder turns over and you go– you know you’re going down this steep slope at the edge, which is, a quite a mess, a lot of little precipices, then a little flat bit, then, uh, some stuff that slid down. A very tumbled, complicated area. Those pictures I showed just now were somewhere, somewhere down here.

I’m not sure exactly where they were. Same sort of thing off New York, same sort of continental shelf, the same sharp edge and the steep slope down onto the plain at the bottom of the shelf. Well, when you get down to the bottom, you’ll find yourself on a more or less flat plain consisting of stuff which has slid down the slope.

Then when you go out a little further, you’ll begin to find hills. This is an echo sounder record. Here’s the surface of the sea, and the ship has steamed along, taking a record of the depth of the sea.

And you really get rather splendid records of the shape of the hills on the bottom. And not only do you get the shape of the hills, you get a little insight into what’s underneath. You see, this is clearly sediment that’s filled up a valley, and you can see it’s in layers.

You can see the layers here, and you can see the bottom where the hard rocks are. And similarly here, going down here and coming up here, and a little valley filled with sediments. Some more sediments up in this little, little valley here.

Uh, very little on the, on the tops. So that by using an echo sounder, which is simply a machine on the bottom of the ship that goes ping, and after a little while the sound goes down and comes back and says rather more faintly, ping. So that you get the thing going along, and by the time the echo… by measuring the time the echo takes to come back, you get a map of this sort.

And not only do you get a map, you also get some penetration into the bottom, and you can measure the thicknesses of the sediment. On the continental shelf, um, you generally can’t penetrate with a simple device like this. You have to use explosives.

You throw explosives out from the ship, and you can get echoes from sediments several miles thick in, in, in that way. Well, you want naturally to see what these sediments are like, and you have a corer. It’s simply a tube with…

This is the tube. You can have a tube almost any length you like, twenty feet, fifty feet, sometimes a hundred feet long, with a great big lead weight on the top end here, and a release here, and an arm, and a weight hanging down. On the bottom of this piece of wire, there’s a weight.

When the weight touches the bottom, this lever flies up. It unhooks this thing here. This weight falls and takes the tube down and drives it into the bottom, and then you haul up on your cable here, and if you remember to connect this piece of cable, you pull the thing out of the bottom.

If you haven’t remembered, of course, it falls away altogether. Um, and you come up with a cylinder of the sediments from the bottom of the ocean. It’s not all that an easy operation.

There are tricks of the trade for getting, uh, good cores out, out of the bottom. There’s a certain amount more on this thing. This is a machine for measuring heat flow through the bottom, and there are various instruments attached to the side of, of the corer.

But all I need at the moment is that this is the way that you collect, collect samples of the sediment from the bottom. And when you’re just at the bottom of the slope, you’ll find that the sediments are things that have slid down the slope. They’re shallow water sediments that have slipped off the continental shelf down the edge to the bottom of the deep sea.

And you find bits of wood, old beer bottles, all kinds of things, um, spread out at the bottom of the s- of the slope. Then as you get away from the continent, you’ll begin to find white sediments, which are the remains of small animals which have lived near the surface and have died and fallen down. Another important instrument is the camera.

This is a deep-sea camera. Thus, the camera is here. This is a camera, and this is a light.

And you let this thing down to the bottom, and when this weight touches the bottom, the cam… the light flashes, and the camera takes a picture, and the film is wound on. And this is a sound transmitter which transmits upwards and tells you that it’s taken its picture. Then you haul it up a bit and let it down, let the ship drift a little way, twenty feet or so, let the weight down again.

It touches the bottom, takes another picture, and you go hopping along, taking pictures of the bottom as as you go, as you go along. And you really get, uh, quite good pictures with this rather simple device. I’ve got a few.

I thought you might like to see a few of these pictures. This is a rather monotonous view of the bottom. um, just, uh, just enough current, uh, to make ripples.

Um, the, the compass, of course, is attached to the camera. It’s not on the bottom of the sea,

(laughter)

is not covered in compasses. Uh, this…

(laughter)

this pic– all these pictures are something like six, six, or eight feet across, that kind of thing. And this is a common sort of picture in the area, uh, before you got to the hills on the, uh, at the bottom of the slope. Taken–

these are all taken in the Atlantic. There’s a fish there which I should think has died because it otherwise it would have run away. You’re beginning to get the white sediment here from the animals that have died near the surface.

Again, you’ve got the white sediment and a few pieces of, uh, uh, of stones. Um, what these are, I don’t quite know. There are a lot of holes.

There are a lot of bumps and holes. Um, there seems to be something in them, so I suppose they’re so– they’re home to someone, and doubtless someone lives under this thing. But exactly what does, I’m afraid I don’t know,

(laughter)

not being a biologist. Uh, that is more peculiar still. I suspect what’s happened there is that the camera has been pulled along the bottom. I, I, I don’t think–

(laughter)

(laughter)

(coughing)

I don’t think it’s fish going in for agriculture. The, the cloud of, the cloud of mud here is a little characteristic, I think. I think the camera’s pulled along here and, and kicked up the mud, and the current is taking it away.

But you often get things in these pictures that are very difficult to account for. Here’s a little more entertaining ones. These are animals.

They’re not plants because there’s no light down there, and plants, of course, photosynthesize with light, and so these things must be animals. They’re rather jolly colors. They’re, um, sort of pastel colors, pinks and blues and greens.

They go black after you hoist them out into the air. So the ones you see in museums are always black, but in situ, they’re quite jolly colors. These are most extraordinary things.

They’re manganese nodules. They are… Inside, there is an object, a little bit of stone or a shark’s tooth or something of that sort, and the, the material around it has been deposited from the water and has grown– the thing’s grown outwards like an onion, and they consist predominantly of manganese oxide, iron oxide, um, and small amounts of copper and zinc.

And there’s a good deal of excitement at the moment as to whether it is possible to dredge these up and use them as a copper-zinc ore. Uh, they’re no good as a manganese ore. You can’t sell manganese ore.

There’s so much manganese in the world that the price is only a few cents a pound. And I think if you delivered these things free to a manganese factory, they would probably turn them– turn you away. But they are potentially interesting as a source of copper and zinc.

And it really is a very curious thing that these things should be deposited in some places so densely that you should get this almost complete pavement of them over many thousands of square miles. And it’s still odder because if you go down below these things, you don’t find any. It appears to be a layer on the sea bottom.

and I haven’t the faintest idea why it is that these are formed on the sea bottom, but apparently weren’t formed in the past, uh, below the, in the earlier sediments. I don’t understand this at all. It has been suggested that the worms come up underneath them and nudge them up, but I don’t really believe it.

(laughter)

So there’s a, a thing I don’t understand at all. These things are being dredged by the Japanese, and it may well be that they are a worthwhile, uh, resource. This is one of them with a cut through in a section.

(door slams)

It’s got a stone of some kind inside it, and these are the layers of manganese oxide which have gradually built themselves out around the outside. Here’s some more of these animals, um, growing, I think, on a rock there probably. Yes, we’re getting into a rather rockier part in these little, probably on one of these little hills.

The further we go out to sea, the rockier it gets. You get these very curious angular pieces of rock. This very much surprised me when I first saw these.

Um, apparently, uh, all these rocks are lavas, and they come out of volcanoes on the floor of the ocean. And of course, if you f-flow, uh, molten rock into cold water, it solidifies and not unexpectedly cracks, and it apparently cracks, uh, into these rather irregular pieces, and it holds together for a while and then gradually breaks up. You get iron and manganese oxides deposited in the cracks, and it forces them apart and breaks them up rather like rock is broken up in the Arctic by water getting into cracks and freezing.

But it’s very characteristic of the sides of these volcanoes that you get these, um, irregular broken up lumps of rock. This is a dredge for recovering rock. It’s, uh, simply a, a steel mouth here and a bag made of rings, rather like chain mail.

The fact is that the people who make chain mail are not– haven’t got many orders nowadays, and they’re very glad to make, um, dredges for, uh, for, for rocks. And you pull this thing along the bottom and scoop up the rocks. You’re very liable to get it caught, and the trick is to have a weak link here, so that if the thing gets caught up on a bit of rock that’s too big for it, it will break here.

This will flop away, and you can pull and the thing pulls clear, and you can usually get it back before the cable breaks. The trouble is, if the cable is going to break, the strain is greater at the top because there’s the whole weight of two miles of cable, and it’s liable to break near the surface, and you lose not only the bag, but all your cable, and you lose many thousands of dollars worth of equipment. So it’s very desirable to have a weak link in here so that the thing, uh, will pull clear.

Here’s the thing come back again, and the rocks being shaken out of it on board ship. That’s a Scripps ship, I think. This is an English ship.

They’ve got a few rocks. You don’t always get very much. They’ve got a dozen or so this time, and they’re busy having a look at them.

Well, here’s some more pictures of these rocks, and you can see this white sediment, which is formed by the remains of little animals, um, which live near the surface and fall to the bottom. This is the side of a volcano in the Atlantic, not very far from the Canary Islands, I think these were taken. Here’s some rather bigger rocks, all with this manganese oxide deposited on them.

You can see here these rounded forms. Uh, these are all coated with manganese and iron oxides, which have, uh, come out of the water and deposited themselves on the bits of lava. You see that very well here, these rounded forms.

That’s a color photograph showing the colors aren’t really, uh, very thrilling. Lava isn’t a very good subject for color photographs. Um,

(cough)

I think one gets a wrong idea of the amount of the number of fish in the deep sea by looking at the photographs I’ve shown earlier, because I think the camera scares them away. You lower a camera and the, uh, the lights flash and so on, And I think the fish swim away. But if you put a can of fi– a can of fish here, these are dead fish, cod’s heads and things, in a, a can, and you attach a camera to it and leave the whole thing there for a quarter of an hour or so and then start taking photographs, then you see all these eels and, uh, things of this kind.

You often see tracks of these things on the bottom, but you practically never see them in the ordinary photographs. It’s only if you leave things to settle down and put some food there that all these gentlemen, and ladies no doubt, uh, will come and, uh, see what’s going on and trying to get a free dinner. Rather surprisingly, you really get some quite quite big fellows.

Uh, this is a big shark. Uh, I had no idea there were sharks this size in the deep sea. These are taken in depths, uh, exceeding a mile.

And that poor chap, of course, his, his nose is too big to go in the can. These were taken, these last two photographs were taken by John Isaacs of Scripps, who developed this method of photographing animals by giving them some food and leaving them there for a while, and then ta– and then taking the photograph. Well now, you go, you go out away from shore, And you get more and more of these volcanoes, And you’ll get into what is certainly the biggest ocean range– uh, biggest mountain range in the world.

The mid-ocean ridge goes right away around the world and is much the biggest mountain range that there is. It starts over here in Siberia near the mouth of the Lena River, runs across the Arctic, comes down just to the west of Spitsbergen, Down through Iceland, past the Azores, down round the Cape, and in the middle of the Indian Ocean, it divides. One branch goes up into the Gulf of Aden and the Red Sea.

The other branch goes south of Australia, around here, into the western– into the Eastern Pacific, up here, int-into the Gulf of California and, um, ends there. Emerges again, Cape Mendocino, you know, and runs up off the west coa- off the west coast of Canada and runs in into Alaska. And this is a mountain range that not only runs all around the Earth, but is also an extremely rugged mountain range.

The relief is quite comparable to that of the Himalayas. In places like the Azores, you get quite large mountains sticking out above the surface of the sea, and there’s another, um, ten or twenty thousand feet, um, down below the sea. So that you really get extremely large mountains, um, along this line.

The sections are reasonably spectacular. This is a section from Marth- Martha’s Vineyard across to the coast of North Africa.

You’ll come down across the shelf, go down the slope, then there’s a good deal of rubbish, uh, Coming down, um, deposited here. You’ll get a flat plain. It doesn’t show very flat here, but it is in most places pretty flat.

Then you get into these hills and get into the large mountain range, and then the same thing, the flat plain, some islands, and then the, the, the shore again. Perhaps this one is clearer. Um, here’s the, the continent, and here are the hills, and here’s the mid-ocean ridge, this great mountain range.

And in the middle of it, there is a valley. See the valley there, and the valley there, and the valley there. And this valley is continuous all the way along.

Here’s a number of sections which we took in the North Atlantic. Every– These sections are every few miles to show that this valley really was continuous and showed in all the sections.

So that you’ve really got a new world. You’ve got things that are quite different from what you see on land. The rocks are different.

We’ve got all the rocks are lavas. You don’t get the typical granites of the continent. You get these dark black basaltic lavas, which you get on the continents, but they’re not the typical rock, whereas they’re the universal hard rock of the deep oceans.

Um, the mountains are not fold mountains. The mountains on the continents, the Alps for example, are folded by horizontal compression and are all twisted. You look at any cliff, you see them all twisted.

Here, all the mountains are volcanoes. And then you’ve got this extraordinary valley going down the crest of the mountain range. This is something quite different.

There’s nothing comparable to this anywhere on the continents. And then you have the most extraordinary distribution of earthquakes. The earthquakes, which are marked by these black dots, lie along this central valley.

This is a rather old diagram and doesn’t show them quite as well aligned or as clearly as they are on a modern diagram, but the modern diagrams are rather large to make decent slides out of. But I think you can see that all the way through the Atlantic, around the Cape, and then these two branches, one here and one here, there are earthquakes. I’ve got a modern diagram of a little piece of it.

This is the piece in the North Atlantic, and you see how well they’re aligned. And, as you come into Iceland, they get spread a bit, but on the whole, down here, they’re extremely well aligned, and there’s a branch that goes off here into the Mediterranean. But all this bit is very accurately aligned along this valley.

So that you’ve got earthquakes running all the way along the central valley of the mid, the mid-ocean ridge. It runs ashore in Iceland. Now, I should have said before I show that slide that the nature of these earthquakes is such that it shows that the crack is opening.

From the motion in an earthquake as recorded on a seismograph, you can tell what kind of motion has occurred in the earthquake. Is it a compression, or is it a cracking open, or is it a pushing over, or is it a thing like that? And these earthquakes on the mid-ocean ridge are a cracking apart so that it is certain that along this valley you’ll have a cracking open, and that is doubtless why the valley is there.

And of course, when it’s cracked open a bit, you’ll get lavas come up to fill it. You can’t make a permanent crack of great depth, uh, in the surface of the earth without lava coming up and filling it. And where you run ashore in Iceland, You can see these cracks.

This is one of the cracks, um, where there’s been Then these are all lavas from the volcanoes of Iceland, and this is a crack running through them. And it’s obviously a fairly recent crack. If that… before…

If that crack stays there for a great time, um, either it’ll get filled up with bits, uh, coming off the sides or it’ll get filled up with, uh, beer cans or something of the kind. It, it, in a few thousand years, that will get filled up one way or another, so it must be quite a recent thing. It’s quite a large thing.

You can see there’s a man standing here. He’s about, I don’t know whether you can see him from there. He’s about twice the height of my arrow.

There are his feet, and there’s his head. So this crack is fifteen or twenty feet across and a few hundred feet deep and is in these lavas, and doubtless it’ll crack open again, and then you’ll get lava coming up, and it’ll get filled up. And it’s rather nice that one has in Iceland a really almost unique place where the central valley runs ashore and you can see the process of cracking open going on.

You see the extent of the differences from the continents, the rocks, the kind of topography, this extraordinary crack, these rows of earthquakes which you don’t quite get on, on land. And there is also a difference in, which I pointed out earlier, that the crust of the Earth is thinner in the oceans than it is on the continents. That has been found by the same sort of seismic method that was used on shore.

This is a, um, a seismograph. Actually, it’s just a hydrophone. It sits in the water and transmits signals by There’s an aerial sticking up above, and it transmits signals back to the ship, and the ship drops explosives, and the records are made, by this h-hydrophone, which is connected to electronics inside the buoy and transmits the signals back.

And by these means, I don’t want to go into the details, one can investigate the thickness not only of the sediments on the bottom of the sea, but the thickness of the earth’s crust, and it has been found that it’s thinner at sea, uh, than it is on dry land. On land, the crust of the earth is about thirty kilometers thick. At the bottom of the sea, it’s only about five kilometers, uh, below the bottom of the sea.

And a tre-, a tremendous effort has been spent on developing all these techniques. I mean, one doesn’t, it– It isn’t too easy to make all this equipment work at sea and to handle all these explosives without blowing oneself or the ship up. And the whole– a whole new technology has had to be developed since the war for doing all these things and finding all this information.

And this is one of the most important of the techniques, the technique for doing seismology at sea with artificial shocks produced by explosives. It’s also, of course, very widely used on land as well. And we also have seismographs that can be put on the bottom of the sea and then called back.

You have an instrument, and you throw it over, and it sinks to the bottom, and you leave it there for a month or so, and then you come along and you whistle to it, and it recognizes its master’s voice and comes up and can be collected again. It’s not an occupation I’m very fond of because these instruments get more and more complicated and more and more expensive, and I really don’t like throwing ten thousand dollar instruments into the sea, half a dozen of them maybe, and hoping that a month or two later they will, they will come back when they’re called. But of course, um, I belong to an older generation who feels that half a dozen things costing ten thousand dollars, is a serious consideration, whereas of course graduate students don’t mind at all.

They consider it entirely natural. Well, you know, they come home and say, “Well, after all, you can’t make omelets without breaking eggs.”

(laughter)

Well, I’ve left to the last the greatest and most extraordinary difference between the continents and the oceans. The continents, the rocks of the continents are of all ages, almost back to the age of the solar system. You can find rocks on the continents of all ages from things that have just been formed back to 4,000 million years.

You’ve got the history of 4,000 million years embedded in the continents. But in the oceans, you’ll practically never find a rock more than 150 million years old, and most of them are a good deal younger than that. And there’s an enormous contrast between these very old rocks on the continents and the relatively young rocks of the oceans.

It means, of course, that the oceans, the individual oceans, are a relatively temporary thing. That they’ve only been there, the Pacific, the floor of the Pacific, the floor of the Atlantic, the floor of all the oceans, has only been there for a small fraction of geological time. And I think this is perhaps the major intellectual discovery in earth science, um, of recent years, this sudden realization of the… this fundamental difference between the temporary young ocean floors and the permanent old continents.

It came, I said the sudden realization, it actually came a little slowly. At first, of course, when we recovered rocks from the bottom of the ocean, we weren’t very surprised to find they were young. It seemed very natural.

Naturally, the floor of the ocean is covered by the skeletons of animals that have only just died. You’d expect it. You wouldn’t expect to find old rocks.

Everything’s covered up. But then we started to, uh, look systematically for deeper rocks by running the dredge up fault scarps. If you’ve got a place where there’d been a fault and there was a great step, you could pull your dredge up the side of it and, um, recover rocks, um, from this scarp.

And then you found you’ve got a whole succession, the older ones at the bottom, the younger ones at the top, but only a hundred and fifty million years of them. You never found older rocks. And since then, which I shall probably talk about next time, uh, there’s been relatively deep drilling in the oceans, and this has also turned up relatively young rocks.

And this, I think, came as a bit of a shock to the people who had been studying the Earth because there had been a very widespread belief that, at any rate, most of the ocean floors were very old, that they’d always been there, the continents had always been where they were, and had always had oceans in between. The other view was that they’d gone up and down like a yo-yo, and had sometimes been continents, and sometimes been oceans. And it’s very interesting now to read the addresses, like this one.

Unfortunately, there hasn’t been a geological one, uh, here, but in many other places, in the Geological Society of America, the English Geolog-Geological Society of London, you can read the presidential addresses with the most dramatic accounts of the floors of the oceans going up and down and, um, all the continents named, the continents that used to be in the middle of the Atlantic Ocean, all with names, and a whole elaborate mythology, which was absolutely total imagination. Uh, there was no basis for it at all. Um, because in fact the floor of the oceans are not only very young and certainly haven’t, uh, gone up and down, they’re also quite different from the continents and certainly have no intention of coming up and down.

They’d look most peculiar if they did. They, they’d look quite different from a continent. So that this is really a quite new thing.

We are starting again. We have the oceans, and they’re totally different from the continents, and one ha-had to start again thinking quite anew in different terms and gradually find find out how to think about the floor of the oceans, how to talk about it, what one was dealing with. One shouldn’t talk too much by analogy with the continents.

One had to develop, uh, new modes of thought about the about these areas. Well, um, clearly if the oceans are breaking open are breaking open along the center, then the sides must be moving away. On each side of the mid-ocean ridge, for example, in the Atlantic, you have areas with virtually no earthquakes, and you have the line of earthquakes down the middle, and you know that it’s cracking open, so presumably the bits on the two sides, which are usually called plates, are moving away to each side, and new ocean floor is being formed in the middle.

So you have the idea that the ocean floor is continually moving away from the center of the ridge and new ocean floor is being formed in the middle. So that you should have brand new ocean floor in the middle and rather the older ocean floor as you go to the edge. And in a place like the Atlantic, there are not only no earthquakes on these plates, there are no earthquakes on the neighboring continents either.

There are virtually no earthquakes of any importance in Europe, apart from the one that Candide got into trouble with in Lisbon in seventeen fifty-two. Um, exactly where that was, I don’t know. I suspect it was that Candide’s earthquake, uh, was somewhere on that side branch that I showed, uh, in an earlier slide.

I showed a string of earthquakes going out from the mid-ocean ridge across, uh, towards Portugal and Spain. And I think probably the, uh, this big Lisbon earthquake of 1752, which was a very spectacular earthquake, was on that line and was a good deal south of Lisbon, but I wasn’t there, so I don’t know. And of course, there weren’t any seismographs there either.

Well, what was I talking about? I know. Um, there are not any considerable number of earthquakes, either in Europe or in West Africa, or in the eastern part of South America, or in the eastern part of the United States.

None of these are seismic areas. And if the ocean floor is moving, is moving out sideways, then clearly the continents have got to move too, because otherwise you would have distortion at the edge, the things would be compressed or something of this sort. Maybe you would have a mountain range formed, but in fact everything is perfectly peaceful, and, uh, one has the very strong suspicion that, um, North America is moving away from Europe.

And in fact, it seems to have had one or two abortive tries at it first. Uh, the– there is in fact, there appears first of all to have been a split, um, over on the eastern side of the Atlantic. There’s a little bit, there’s a thing called the Rockall Bank, which seems to be a little fragment of continent that’s got stranded in the middle of the Atlantic.

It’s rather bad luck for it that it didn’t constitute an island. There is just a little island sticks up, just a rock. But this appears to be the remains of the original split.

It seems to have split first of all on between Rockall and Scotland, and then it decided it didn’t like this, and it split again between Rockall and North America. And North America wa-went away, leaving Rockall, uh, sitting in the Mid-Atlantic with a bit of ocean between it and Scotland. And I think the middle…

It looks now from the oil company’s results that have just been published, if there was also an abortive split, uh, down the North Sea. There’s a big crack in the middle of the North Sea, which has been completely filled with sediments and is the place where in fact the North Sea oil discoveries are. Uh, apparently another abortive split in the middle.

So there are quite complicated histories of the s– uh, uh, the widening of the, of the Atlantic Ocean. Well, this raises all kinds of problems, obviously, about what has been, wh-what has been going on, um, how you get rid of ocean floor because you can’t go on forming ocean floor and just have more and more of it because there won’t be room for it. You have to find what has happened to the ocean floor, where it’s going to, and, uh, so there are a number of problems connected with this.

There are problems connected with the back history. If we extrapolate back in history, what were things like? And then there’s the problem connected with the general improbability of the whole story.

I mean, clearly, you’re going to have some difficulty in persuading people on the evidence I’ve so far giving, given you that this thing is in fact correct. And one wants confirmation that these things have really happened. And I think this is all rather a good example of how science works.

You have a whole, a new group of people coming into a subject, a new technology, a new group of ideas about how the subject should be pursued, and then you get a whole lot of new ideas, a whole lot of new facts coming out, and you have theories proposed about this. And some people believe them, and some people don’t believe them. Uh, it’s a matter of temperament, whether you believe new ideas or whether you would rather not believe them.

And you’re not necessarily any better for believing them because they may be wrong. Um, sometimes it turns out that the people who refuse to believe them are the wise ones. But I think the proper thing to do is when you’ve got to the stage which I’ve described, is to say, “Well, now, what,” what can we do to find out if all this is right?”

We’ve got this rather tenuous evidence depending largely on the earthquakes down the, the mid-ocean ridge. This rather tenuous evidence that new ocean floor is being formed and the continents are moving away from each other. Well, what sorts of other evidence can we find?

What can we do about it? How do we make the things stick, or how do we disprove it? And this is much more important than arguing on inadequate evidence, whether it’s right or not.

There are always a great many people who are willing to go to the stake, so to speak, for things that are quite uncertain, um, on both sides I mean, there are people who come up with the highest indignation and say they’re quite sure this is all wrong. and then there are people… I remember Keith Runcorn, who’s a professor of physics in Newcastle, coming up to me one day and asking me whether I believed something or other.

I forget what it was. It was something to do with this subject. And I said, “Well, Keith, I really don’t know.

I’m not sure.” And he said, “Teddy, either you’re for us or you’re against us. There’s no two ways about it.”

I mean, it was just like, uh, being buttonholed by the Pope. Um,

(laughter)

But I, I think it’s a much more profitable way of looking at things to say what, uh, never mind whether it’s right or wrong, what sort of things can we do which will show whether this is right, this is right or not. And these ideas lead to rather definite predictions. For example, I’ve said that the rocks in the middle of the oceans, the igneous rocks, the lavas that have come up should be quite new, and as you go away, they should get older and older, but they will of course be covered with sediments.

And there should be thicker sediments out to one side, and these sediments should be young on top, and you go down through them, they should get older and older, and they– at the bottom, they should be the same age as the lavas, and this should be, uh, older than the rocks further in. You should have a progression of age as you go out. And one of the things you naturally do is to try and drill down and see if this is true.

And there are also other ways of seeing whether you’re right or not. And what I propose to do in the next talk is to discuss the evidence which consolidates the things I’ve been saying this time. I mean, this time I’ve been talking about rather obvious things where you just say, I take a camera and or I take a dredge, and I look at the rocks, and I look at the earthquakes, and I made a sort of plausible case for the widening of the Atlantic, which presumably also works with the narrowing of the Pacific.

And now I have to get over the difficulties. I have to explain how we get rid of the ocean floor, and I have to produce other evidence from drilling and from other things to show that this is really so. And I have to look back in time and see what has happened in the past.

And in the next lecture, I propose to do this. And there is– We’ve been much luckier than you could expect. We, in fact, have, uh, quite unexpectedly obtained a complete timetable, uh, for all these events, and I hope to describe next time, uh, how that was done.

It’s just a little bit more sophisticated than the rather simple-minded things I’ve been talking about, but, uh, not very, not very much so, and I hope on whatever the date is to talk about that.

(applause)

[00:57:01] CHAIRMAN:
Just to remind everyone, the next lecture is two weeks from today on February the third, the same time and place. The meeting is open for a few questions if there are questions from the audience.

[00:57:19] AUDIENCE MEMBER:
I was wondering, is the San Andreas Fault more comparable to the crack than the moving plates? In particular, is the earthquake movement similar?

[00:57:29] SIR EDWARD BULLARD:
Sir, I-I want to interrupt for next time. Um, what is happening? Uh, I’ll just say very briefly now what’s happening.

The coastal part of California is moving north relative, relative, relative to the rest. Uh, and the plate, um, is, is going north and gradually going down under the Aleutians. So I’d like to describe this next time, but I’ve kept away from California because it has a little more complicated history than the Atlantic.

I thought I’d talk about the Atlantic this time because it has a rather simple, um, I can give a rather simple account of it. I will talk about Cal-California and the San Andreas Fault next time. Yes?

[00:58:13] AUDIENCE MEMBER:
What about submarine canyons?

[00:58:15] SIR EDWARD BULLARD:
Oh, yes. Submarine canyons, lovely things. Um, on the, on the edge of the continental shelf where it goes down, there are canyons.

They are roughly the same sort of size and depth as the Grand Canyon. They’re very spectacular features. They’re, they’re nicks in the edge of the continent.

There’s been regular controversy as to how they’re formed, and I think there’s probably, uh, more than one kind of them. They’ve pretty clearly been eroded out by something, but it’s a little difficult to see what it is that cuts them. There’s a very big one, more or less off New York.

And I think, at any rate, those ones fairly far north are probably cut by the tremendous flow of muddy– of mud and water at the end of the ice age. I suspect that you had tremendous floods on land when ice dams broke and that kind of thing, and a whole flood came down and brought down mud and rubbish, and that this cut these things. But I don’t know, and I am very puzzled about things like the Scripps Canyon down at La Jolla, which is cutting quite hard rocks, and I really don’t know what does that.

And there are some of them in the tropics where it can’t be the melting ice. There’s one off the mouth of the Congo. And I think there is a problem as to what it is that these rocks on the continental shelf are not very hard, they’re sediments, but still it’s not very easy

(coughs)

to cut a valley in them. They certainly aren’t carved like the Grand Canyon above sea level. They go right down, um, out to the edge, they go, They go–

(coughs)

They’re cutting the edge of the continental shelf, and they go right down the whole map to depths of, of, of many thousands of feet, and I don’t believe they’ve been cut, uh, when sea level was lower. I don’t think sea level’s gone down more than a few hundred feet, and I don’t think these things can be cut like the Grand Canyon. Yes.

(cough)

[01:00:24] AUDIENCE MEMBER:
Uh, is there any difference in the, uh, uh, structure of the areas of the Earth that are having these strange phenomena of people disappearing, like off of Florida Keys?

[01:00:35] SIR EDWARD BULLARD:
Do people disappear off Florida Keys?

(laughter)

I’m sorry, I don’t know this one.

(laughter)

And… What do you make of that?

(laughter)

No,

(laughter)

I don’t know the joke. I’m sorry.

(laughter)

I mean, I never had— I’ve never had this.

[01:00:56] AUDIENCE MEMBER:
There’s an area— the airplanes have gone through, and they’ve never been found again.

[01:01:01] SIR EDWARD BULLARD:
Ever again?

[01:01:02] AUDIENCE MEMBER:
The Bermuda Triangle. Sure.

(laughter)

[01:01:06] SIR EDWARD BULLARD:
Well, I, I— I don’t know.

(laughter)

(background chatter)

(laughter)

[01:01:20] AUDIENCE MEMBER:
Since, uh, you can find the marine fossils in the Midwest, western part of the United States, I’m, I’m, uh, somewhat curious whether that, uh, ch-change in elevation of the sea was simply due to the fluctuation of the ice ages, or whether in fact the continent is being lifted up and, uh-

[01:01:36] SIR EDWARD BULLARD:
I think there it’s been lifted up, um, uh, lifted up undoubtedly. Um, the western United States is a very interesting place. The continent has, in fact, probably overridden one of these mid-ocean ridges.

Quite complicated things have been happening. Of course, a lot of these fossils are shallow water fossils.

[01:01:56] AUDIENCE MEMBER:
Right.

[01:01:56] SIR EDWARD BULLARD:
Uh, I mean, you don’t need, uh, you don’t need to lift it up two miles from the bottom of the deep ocean. Uh, um, it looks as if the sea went down a few hundred feet during the Ice Age when a lot of water was tied up in ice caps, and you’ve got people living on the continental shelf. On the continental shelf around England, for example, you find remains of early man.

Now, we, we’ve dredged up occasional flint axes and, uh, carved bits of bone and things of that sort. That’s right. I think it– this has effectively been, uh, been dry land.

And if you melted all the ice now, if you melted all the Antarctic ice, you would get a rise of a couple hundred feet or something like that in water-in the water level. But I think these fossils on the tops of hills, I think the land was mostly emerged. Yes?

[01:02:52] AUDIENCE MEMBER:
Aren’t these valleys,

(coughs)

submerged valleys, filled valleys in, uh, Lake Dana, Marcellus, Buffalo, Off New York, our own Salina?

[01:03:06] SIR EDWARD BULLARD:
I’d say rather, a legacy of stream action that’s so connected with the rivers.

[01:03:10] AUDIENCE MEMBER:
Well, the trouble is they go so deep. You see, take the one over in York, that’s the canyon.

[01:03:15] SIR EDWARD BULLARD:
Canyon, yeah.

[01:03:16] AUDIENCE MEMBER:
Um, I haven’t got a microphone on.

[01:03:17] SIR EDWARD BULLARD:
Nope. Um,

(Can you hear the question?)

What?

(laughter)

Oh, the question.

(laughter)

Whether they went cut by streams. Um, I must– This is obviously the first suggestion.

They do look rather like that, but the trouble is they go down about ten thousand feet at the other end. I mean, the top part may have been during the Ice Age, but I don’t think the sea level’s been down ten thousand feet. You can follow these things right out on the floor of the deep ocean.

And the Mediterranean was then? Uh, the Mediterranean dried up. Yes, indeed.

The Mediterranean had salt on the bottom and dried up completely. But these things– And I don’t believe the Atlantic has been dry in the The last hundred thousand years.

It seems to me rather a problem. I mean, I’m not saying I know how the canyons were cut, but I find it somewhat difficult to believe they were cut by rivers. Uh, so again, I mean, some of them were.

Uh, the Hudson Canyon is not very clearly connected with the Hudson River, but the Congo Canyon is. Well, I mean, there’s a very shallow thing across the shelf, and then you come to the canyon. The one off the Congo is very clearly connected with the Congo, and there’s one off the mouth of the Ganges.

Yeah. I, I mean, I think these things are probably a number of different mechanisms, but I find it difficult to believe streams cut the bottom off. Yes?

[01:04:50] AUDIENCE MEMBER:
Do you think these turbidity currents, um, could be abrasive enough to cut the rock?

[01:04:55] SIR EDWARD BULLARD:
Well, I, I think… How do I know? They break cables.

(coughing)

Um, you get earthquakes. If you get an earthquake near the continental edge, even quite a small earthquake, it very often sets off a slide, and a mass of water and mud goes running down the slope at about sixty miles an hour. Apparently the– there’s enough sand and mud in it to make it heavier than the surrounding water, and it goes off at about sixty miles an hour and cuts cables one after the other.

And you can get half a dozen cables cut over a period of an hour or two as the stuff slides down. And if you can cut a cable, you must have a certain abrasive power. Um, but, I mean, how do I know?

The-there’s no doubt that there are in places deposits of stuff that’s run down these canyons. There is material running down these canyons sometimes.

[01:05:56] AUDIENCE MEMBER:
What? Like Scripps Canyon?

[01:05:58] SIR EDWARD BULLARD:
Is that- The Scripps Canyon, I, I don’t think anyone knows. There’s a, a sort of trickle of sand that goes down it. There’s some rather nice pictures of, of sort of trickles of sand, but I don’t think in the Scripps Canyon anyone has seen a, a, a, a really big block running down.

Often it isn’t very often you get an earthquake in the right place to set it off. And Scripps, as you know, as you know, Southern California doesn’t have any earthquakes.

(laughter)

Yes.

[01:06:24] AUDIENCE MEMBER:
What is the origin of those very high seamounts that were shown in some of your programs?

[01:06:28] SIR EDWARD BULLARD:
Uh, they’re volcanoes.

[01:06:30] AUDIENCE MEMBER:
Right. Along that plain between the bottom of the slope and the-

[01:06:34] SIR EDWARD BULLARD:
Uh, well, you’ve shown that– this is interesting. You do sometimes get rows of volcanoes, um, not connected with the mid-ocean ridge. For on Hawaii, for example, there’s a whole row of volcanoes.

Runs out, streams out from Hawaii. The more recent ones are above sea level, and then there’s a whole lot of submarine ones. And sometimes one can see fairly clearly what these are.

There are places where, uh, plates are slipping. For example, from the Azores, you’ve got the mid-ocean ridge pulling apart, and you’ve got a, a line at right angles where the plates are moving out at different speeds. You’ve got a pulling, uh, uh, uh, a tearing apart, and there’s been some volcanoes on these.

Yes.

[01:07:23] AUDIENCE MEMBER:
Uh, sir, during the lecture, you said that you didn’t think the, uh, the bottoms of the oceans were rising and falling as a yo-yo, and I wondered if that made me think of Charles Darwin’s explanation for atolls, and I thought that required that the volcanoes be rising.

[01:07:39] SIR EDWARD BULLARD:
Well, yes. Uh, the big example is, when you’ve got a volcano–

(unintelligible)

Well, I mean,

(coughs)

if we build up a volcano, and it sticks up out

(coughs)

of the surface, and then it’s a big load on the bottom, and, uh, in course of time, it shifts down. We’ve got a lot of, we’ve got a lot of mountains in the Pacific that have had tops that have been

(coughs)

planed off by waves, and then have sunk. Uh, what I said was, I don’t think big areas of the sea floor rise up, and if they did, they wouldn’t look anything like continents. Uh, I mean, a volcano obviously builds itself up, and I’m sure you’re right in saying that they, um, find themselves too heavy and s– uh, uh, and sink down again.

I think very fair.

[01:08:24] AUDIENCE MEMBER:
But on an individual case.

[01:08:26] SIR EDWARD BULLARD:
Yeah, on individual cases. And also, also actually, as the plates move out from the central valley, they cool. You see, the hot lava is in the middle, and as they go out sideways, the rock cools and contracts.

And this is why the sea gets deeper as you go away from the, uh, mid-ocean ridge. Uh, bit of sea floor is made in the middle, and as it moves away from the middle, it cools and contracts, and you get, uh, um, deeper water. The theory of this has been worked out rather well.

It seems to fit quite well. Yes.

[01:09:05] AUDIENCE MEMBER:
Is the, uh, layer of rock thicker, um, in the Pacific Ocean than the Atlantic Ocean?

[01:09:12] SIR EDWARD BULLARD:
The films were, uh, simply deadly, I must say. Uh, there was a belief that they were different about, um, just off the wall. A number of people said they were different from Turner to Turner. They are broadly the same.

[01:09:27] CHAIRMAN:
Thank you very much.

(applause)