This edited article about chalk originally appeared in Look and Learn issue number 703 published on 5 July 1975.

Bleriot crosses the famous challk-white cliffs of Dover

If you look at a tiny fragment of blackboard chalk through a fairly powerful microscope, a fantastic world is opened up before your eyes.

Each speck of chalk is seen to have a most unusual shape: here is a tiny white star, there is a small sphere covered with minute holes, there again is a minute and delicate sea shell.

All these white stars and hollow globes are in fact the skeletons of microscopic sea creatures that lived in the sea many millions of years ago.

In their living state most of these animals looked like tiny blobs of jelly less than a hundredth of an inch across. Through the holes in some of the skeletons thin jelly-like tentacles projected out into the surrounding sea water, intertwining to form tiny nets to collect food.

Most of the star-shaped and sharp spiky skeletons are the skeletons of tiny sponges.

Mixed with all these strange skeletons we can also see crushed fragments which are the powdered remains of skeletons of other living creatures, such as sea-urchins.

When all these microscopic and primitive living creatures died their skeletons slowly drifted down to the sea bed, and formed a layer of creamy mud or “ooze.”

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This edited article about caving originally appeared in Look and Learn issue number 698 published on 31 May 1975.

Cavers or pot-holers discover a subterranean world of beauty among the stalactites and stalagmites

Man has been to the moon, climbed the highest mountains, visited the sea’s depths and flown faster than sound. What else is there for an adventurous individual to do? One answer is to scramble deep below the surface of the Earth, to explore the tunnels and caverns that ancient rivers fashioned into a strange and beautiful wonderland.

Not content with exploring these, men have tested their ability to endure long periods in this cold and awe-inspiring world. Milutin Veljkovic of Yugoslavia set the world record for this when he spent 463 days between 1969 and 1970 in a cavern in the Svrljig mountains of northern Yugoslavia. But he was not entirely alone, for he took a cat, a dog and some hens and ducks for company.

Time means little to people when there are no days and nights but the perpetual glimmer of an oil lamp. When David Lafferty went into Gough’s Cave, Cheddar Gorge, Somerset, he tried to keep a check on the passing of time. Companions joined him towards the end of his stay and told him that August had arrived. A surprised Mr. Lafferty had thought that it was only July. Since he had been in the cave from 27th March, this was not unexpected. By remaining in the cave until 4th August in 1966, Mr. Lafferty set up a British record of 130 days underground.

He achieved this in a cave found in 1867 by a Mr. Gough and his sons. They came across it after exploring fantastically beautiful tunnels spiked with stalactites and stalagmites. Behind some rubble, they discovered not only a new series of caves but something else which set their imaginations reeling. Among the rocks lay the skeleton of a man which was estimated to be at least twelve thousand years old. When this man was alive, people had ceased to live in caves. They had learned to build huts and defend themselves with weapons. And they hunted the reindeer, cave-lion and brown bear which, with the mammoth, roamed the Somerset hills.

So why had this early man gone into the Cheddar caves? Perhaps he, too, had gone in search of adventure, like the underground explorers of today, as a pioneer pot-holer of ancient times.

This edited article about the San Francisco earthquake originally appeared in Look and Learn issue number 695 published on 10 May 1975.

The San Francisco earthquake by Graham Coton

In Ancient times the Greeks were convinced that the world was supported on the shoulders of the god Atlas. Occasionally, when he was feeling tired, he would shift his load from shoulder to shoulder, with the result that the buildings on Earth were shaken to their very foundations. In this manner, the Greeks sought to explain away those volcanic convulsions of the Earth’s surface which we know as earthquakes, the most terrifying of all the natural forces of nature.

The average earthquake lasts from a few seconds to a few minutes, but in that brief span of time, they have destroyed whole cities and brought about the death of thousands. It was such an earthquake that struck San Francisco on April 18th, 1906, finally reducing America’s ninth largest city to little more than a heap of smouldering rubble.

It struck at dawn, signalling its arrival by a growling rumble that swiftly built up into a gigantic continuous roar. Seconds later, buildings began to topple, slowly, almost gracefully at first, before bombarding the streets with great pieces of masonry. Wide streets and avenues were torn with crevices six feet wide. Railway lines were buckled and then flung into the air like gigantic javelins. The whole city heaved.

But worse, far worse, was to follow.

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This edited article about Julius Wernher originally appeared in Look and Learn issue number 690 published on 5 April 1975.

De Beers diamond merchants found their precious gemstones in the diamond mines of Kimberley, by John Henry Frederick Bacon

Sir Julius Wernher, head of De Beers great South African diamond combine, was a very worried man. One day in 1906, a report reached him that a Frenchman named M. Lemoine had discovered a way of making first-class diamonds at a cost of less than a penny apiece.

Diamonds are costly because of their scarcity. To flood the market with mass-produced man-made diamonds would ruin De Beers and the world’s diamond industry almost overnight.

Sir Julius acted promptly. He arranged a meeting at which Lemoine was to demonstrate his process to Sir Julius and a number of his friends, all leading figures in the diamond industry. Their idea was that if Lemoine could convince them of the truth of his claim, it would be well worth trying to buy him out at his own price.

On an appointed day, the party assembled in Lemoine’s laboratory. As a precaution against trickery, Sir Julius insisted that Mr. Jackson, an expert employed by De Beers, should mix the chemicals. This was agreed to, and under Lemoine’s instruction Jackson mixed the ingredients in a crucible and placed the crucible in an electric furnace.

At the end of half-an-hour, the crucible was withdrawn and allowed to cool. The solidified mass was then broken up by Mr. Jackson and, to the onlookers’ amazement, a number of fine, uncut diamonds were revealed. The smiling M. Lemoine then invited Sir Julius himself to do the mixing for a second trial. The result was even more successful for, this time, more than twenty fine diamonds were produced.

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This edited article about the Aurores Islands originally appeared in Look and Learn issue number 689 published on 29 March 1975.

Nothing could be seen but the restless waves when the sailors looked out for the Aurores, by Ken Petts

Have you ever heard of the Aurores Islands? You will search a map in vain, for they are not marked. Like many other islands, they have vanished as completely as if they never existed. But that the Aurores did exist about two centuries ago, is vouched for by numerous reports and data reported over a number of years.

They were first reported by Captain Oyardvido, master of the sailing vessel Aurora (hence their name) in the early 1760′s. They were described as a group of islands, situated in the South Atlantic to the south-east of the Falkland Islands. Other vessels reported them and they were finally surveyed by a Spanish ship specially equipped for such work and were duly shown on all maps of that time.

Some years later, the captain of a vessel cruising in the vicinity decided he would take a look at these islands for himself. He studied his chart and altered course accordingly. He reached the spot, but of the islands there was no trace. He checked his bearings and posted a lookout in the crow’s nest. Nothing could be seen but the restless waves.

Had the ocean bed opened up and swallowed them in their entirety? Had Captain Oyardvido mistaken icebergs for land? Mist plays some curious tricks in that part of the world, but it is difficult to believe it could deceive an experienced seaman. At any rate, subsequent expeditions failed to find the islands and eventually the cartographers removed them from their maps.

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This edited article about the sea originally appeared in Look and Learn issue number 689 published on 29 March 1975.

Waves crashing on the seafront by Clive Uptton

Most of us think that the sea consists entirely of water. But in every hundred pounds weight of sea water there are about three and a half pounds of solid materials. Most of them are salts of one kind or another.

If all the salts could be taken out of all the world’s oceans and spread over the continents, they would form a crust several feet thick.

Another surprising thing is that sodium chloride, which is the chemists’ name for the salt we sprinkle on our food, makes up only three-quarters of the salts dissolved in sea water.

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This edited article about soil originally appeared in Look and Learn issue number 687 published on 15 March 1975.

Farmer sowing seed by Peter Jackson

Without the thin, loose layer of soil or earth that covers most of the land surface of the world, there would be no plant life. Not only does the soil anchor and support plants so that they grow firm and upright, but the minerals, water and air trapped in it provide the plants’ food.

If there were no plant life, there would be no human or animal life. We and all the animals, birds, reptiles, insects and even fish live on plants directly or indirectly.

Soil, then, is one of the most important things in the world.

The earth in which plants are growing today was solid rock millions of years ago; and the solid rock of today will turn into soil millions of years hence.

The great soil makers are rain, ice and wind, helped by changes in temperature. These natural forces slowly break up the top surfaces of the rock and grind it into small pieces, or pebbles.

Thousands more years pass and the pebbles are ground down by the same forces, and also by rubbing against each other, into the small particles of earth we call soil. But it is constantly being changed by chemical action and the activity of bacteria and other microscopic organisms. True soil is formed only when living organisms start to become active.

Lichens, mosses and other kinds of simple and hardy plant life gain a foothold in the forming soil. These catch and retain fine particles of minerals carried by the wind and rain, and at the same time absorb or take up from the soil various minerals which serve them as food.

The decaying vegetation also releases certain acids and these dissolve many of the minerals present in the forming soil. The growing mosses and lichens release carbon dioxide which, with water in the soil, also helps to dissolve the minerals.

All this results in a thin layer of organic or living matter being built up on the surface of the forming soil.

Then larger and bushier mosses are able to take root. These trap and hold more minerals in greater quantities. When they die, their remains are added to the top layer which steadily becomes thicker and richer.

At last the soil is deep enough and rich enough to provide the firm support and mineral foods needed by grasses, shrubs and trees. The leaves and bits of bark and stalks shed by these plants fall on the soil and fertilize it, making it still richer. In this way a layer of humus begins to form.

The presence or absence of humus makes all the difference between a sterile soil and a rich and productive one. Humus holds in the soil nitrogen, minerals, gases and moisture essential to plant growth. It also keeps the soil warm so that the seeds of the higher forms of plant life can germinate.

This edited article about the Klondike originally appeared in Look and Learn issue number 685 published on 1 March 1975.

Embarking for the Klondike gold rush by Graham Coton

Gold fever! In the 19th century it could sweep whole continents like a raging forest fire, and the pattern was always the same. There would be a rumour of a strike, and a stampede would begin, first a local, then a worldwide one.

Ships were deserted. Clerks in offices in New York, London and elsewhere headed for the docks. Good men and bad men and even women and children set out for the goldfields.

The first fabulous strike was in California in 1848; the last was the equally fabulous “Klondike Stampede”.

Gold was discovered in vast quantities in the Klondike region of Canada’s Northwest near the Alaskan border in 1896. It was so remote an area that the great stampede did not begin until 1898, being triggered off by the arrival of steamboats at ports on the West coast of America, crammed with gold-rich Bonanza Kings and their loot.

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This edited article about earthquakes originally appeared in Look and Learn issue number 685 published on 1 March 1975.

The devastating San Francisco Earthquake of 1906 by Harry Green

It is not surprising that our superstitious ancestors thought that earthquakes were caused by huge monsters that lived under the ground, heaving about as they struggled to come to the surface.

Today we have stopped believing in these fairy tales. Scientists have discovered that earthquakes are just nature’s way of letting us know that the earth is settling down.

According to geologists, as the scientists are called who study the history of our earth, the world was once a mass of soft and very hot material. Then during millions and millions of years, the outer cover of the earth cooled into a hard crust.

Below its hard outer crust, the earth is comparatively soft and is liable to sudden “bubbling” movements, rather like those in a pan of porridge boiling on a stove.

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This edited article about Glamorgan originally appeared in Look and Learn issue number 684 published on 22 February 1975.

Coal miner by Wilf Hardy

Have you ever seen an old film of a night express as it thunders through the darkness, scattering scarlet sparks and glowing embers? Or the blackened, grimy funnel of a coaster as it doggedly thrusts its bow through the heavy swell around the coast? Or the dull glow on the skyline that comes from the blazing furnaces of iron and steel works?

If you have, you may wonder what these three things have in common. The answer is in a small valley in the county of Glamorgan, South Wales. From this, the Rhondda valley, once came the best “steam” coal in the world, to stoke the boilers of the trains, ships and factories of the world.

Steam coal is one of the oldest and hardest of coals. Highly compressed, its calorific value makes it give more heat than any other steam-raising fuel. For a hundred years it has been of immense value all over the world.

Why is this coal, centred chiefly in one valley, two miles wide by twelve miles long, found in South Wales? Geologists tell us that it is all a part of the general rock pattern of Britain.

Millions of years ago the mountainous country of Wales was involved in a slow and gentle movement of rock layers, helped by occasional earthquakes. Over the centuries a thrust from the south pushed and forced rocks sideways over each other, broke them or “floded” them, until they were crushed up against the harder, more resistant rocks that form the core of Wales.

Although seams of coal throughout Wales were laid down at the same time, the pressure on some seams was greater. Towards the west, the pressure hardened the coal layers into anthracite. Towards the centre of the coalfield, steam-coal was formed, and to the east quick-burning, smoky flaming coal for household use was born.

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