Sand Dunes
• The sand dunes of the Sahara (called ergs, or sand seas) stretch for hundreds of kilometres and can be more than 180 metres high.
• The Saharan winds have rubbed the sand into tiny grains, so the sand is very fine, and therefore very difficult to cross. Travellers avoid the Great Western and Great Eastern Ergs, between Beni Abbes in Algeria and Ghadamis in Libya.
• The Great Western and Great Eastern Ergs cover most of Algeria, the Selima Erg covers more than 4,500 square kilometres in Libya, and the Erg Cherch stretches for nearly 1000 kilometres across Mali and Algeria.
• Ergs are formed by winds sweeping sand into heaps. Some dunes have a gentle slope on the windward side, with a steep drop on the side opposite the wind. Seif dunes are parallel to the prevailing winds and have sharp ridge lines.
• During sandstorms, great quantities of sand can be moved, completely altering the landscape.
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You find out fairly quickly that it isn’t a good idea to get close to ostriches. They are big, can be aggressive, and have very sharp claws on their feet that can kill a human being. Added to this, they can run very fast – 70 kilometres per hour – so you definitely won’t be able to outrun them.
These ostriches have young with them, so they’re especially jumpy. A couple of the bigger birds trot away from the others towards you, watching you with what you imagine is an evil glint in their eyes. You remember hearing that birds like these can be tricked into thinking you’re bigger than you are if you raise your arms over your head. You raise your arms, but this seems to be the last straw for one of the ostriches, which sprints towards you.
The giant bird attacks by kicking out with its feet, which are armed with long, sharp claws. With one blow, you are dead.
The end.
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Click here to find out more about ostriches.
Ostriches
• Ostriches are the largest birds on the planet – up to 2.7 metres tall and 160 kilograms in weight.
• They live in African savannahs and deserts, though they rarely stray into the Sahara Desert.
• Ostriches don’t need to drink – they can get all the water they need from the plants they eat. They also eat insects and lizards.
• The birds can sprint up to 70 kilometres per hour, and keep up a speed of 50 kilometres per hour over distances, covering up to five metres in just one stride.
• Ostriches live in small herds of about ten birds. Their giant eggs weigh as much as 24 chicken eggs!
• These huge birds defend themselves from lions with their long claws – so it’s not surprising that they are dangerous to humans, and kill a small number of people every year (usually on ostrich farms). Like many animals, they’re especially prone to aggression when they have young to defend.
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You cut open the fruit with your knife. Inside there’s greenish-white pulp and dark seeds. It looks quite appetising, and you tentatively take a small bite. Pah! You spit the pulp and seeds out quickly – it tastes awful! The bitter taste makes you thirsty. You take a swig from your water bottle and spit it out before drinking some, in case the fruit is poisonous.
In fact it’s a desert gourd, which isn’t poisonous, just foul-tasting. But you were taking a big chance by eating a fruit when you didn’t know what it was. What were you thinking? You’ve had a lucky escape.
You decide to look for another water source.
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Click here to find out more about the desert gourd.
Desert Gourd
• The desert gourd is a member of the watermelon family. It produces a vine that creeps across the desert floor, each one up to three metres long. It has round fruits the size of an orange, which are yellow when ripe.
• The plant is quite common in the Sahara, as well as in desert-like conditions in many Arab countries, coastal India, and parts of the Mediterranean. It will grow in the hottest climates.
• Although the pulp is bitter and shouldn’t be eaten, the succulent stems of the wild desert gourd can be used as an emergency water source – they can be chewed for their moisture.
• The seeds of the fruit are also edible – they’re best roasted – and are rich in oil. The flowers can be eaten too.
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You start digging your hole for the solar still with your trowel. The ground is hard, so it’s tough work. You need to drink several times while you’re digging. You hope that the water produced by the still is going to be enough. You wait all day, sheltering from the intense desert heat, while the still produces some fresh drinking water.
Unfortunately, it doesn’t produce very much water at all – less than half a litre. It’s not enough to keep you going. You’re already dehydrated when you set off again at dusk. You don’t find another water source in time to save you.
The end.
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Click here to find out tips on how to make a solar still.
Making a Solar Still
• Dig a hole in the ground about 90 centimetres across and 45 centimetres deep. If you can find any, put some green leaves and grasses in the hole.
• Put your container in the centre of the hole, then cover the hole with a sheet of plastic, weighted down with a stone in the centre above the container.
• Anchor your plastic in place with sand or rocks.
• As the sun heats the air inside the hole, water vapour is produced, which condenses on the plastic and runs down into the container. Green plants will help make more water vapour.
• You can also use a solar still to distil pure water from undrinkable water, such as sea water – put the contaminated water in a larger container at the bottom of the hole, with a collecting can in the middle as before.
• Beware: a solar still can also act as a trap for snakes and creepy crawlies, which might be able to get in but not get out again.
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You need water to replenish your supplies. You know how to make a solar still – though that would mean setting it up and then waiting during the day. Or you could just keep walking and hope that you find another water source.
If you decide to make a solar still, click here.
If you decide to look for another water source click here.
You hate retracing your steps, but you think it’s important to wash the wound, which is painful and angry looking. You’re grateful for the bright moonlight as you find the well again and draw up some water to wash your wound. You even find a forgotten tube of antiseptic cream at the bottom of your backpack.
As you set off again, keeping well away from any animals you spot, you notice that there are a few clouds in the sky. The moon’s still shining, but every so often a cloud moves in front of it, making it very difficult to see where you’re going.
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You slow down to a walk. You’re sure this was the right thing to do – sweating makes your body lose salt as well as water, and not enough of either can result in death. You’re not sure where you’re going anyway, so getting there fast isn’t going to make much difference.
There are some strange barking and whooping noises coming from high ground to your right. You think it sounds a bit like chimpanzees, though you know that chimps don’t live here. As you walk, the sounds get louder – and some of it sounds like laughter! Suddenly you spot them, dark shapes amongst the rock. It’s a group of hyenas. What should you do?
If you decide to run away and hide, click here.
If you decide to walk confidently past them, click here.
The wind is stronger now. It grabs your scarf and almost whisks it away. You wrap it around your mouth and nose in the sandy air, and have to put up your hands to shield your eyes. It’s difficult to see anyway, because the m
oon is behind clouds.
The wind is howling now, the sand begins to whirl, and soon you can hardly see anything at all. The sandstorm is getting worse. You have to shelter somewhere fast.
If you decide to shelter behind some large rocks on higher ground, click here.
If you decide to shelter beside a nearby dune, on lower ground, click here.
You jump down into the wadi bottom and walk along the dry stream bed, which is rapidly turning to mud as the rain becomes heavier. You start to become alarmed at how quickly the thirsty ground has become thick, cloying mud . . . and you realise that this is a bad place to walk in a heavy downpour. You need to get out of the water and into some kind of shelter – fast!
You make for the side of the wadi . . . but as you do so there’s a roaring sound, and suddenly a huge torrent of water comes rushing around a bend in the dry river bed, sweeping you off your feet like a tsunami. Every time you come up for air, spluttering, the swirling water drags you down again. Half-drowned, you are bashed against a large rock.
The end.
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Click here to find out more about flash floods.
Flash Floods
You might not have thought you’d end up being swept away by a flood in the middle of a desert, but flash floods are one of the greatest perils of deserts around the world . . .
• Storms in deserts don’t happen very often, but when they do they can release a huge amount of rain very quickly.
• Flash floods can happen without warning. The storm that feeds the flood could be miles away.
• Be especially careful in canyons, which can channel water like a giant water hose.
• In the US, on average, flash floods are responsible for more deaths than hurricanes each year.
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You struggle in the horrible, cloying quicksand but it only makes you sink further. The backpack is heavy and the bottom of it is already getting wet. You’re very cold, wet, and now you’re starting to really panic.
Then you have an idea: what if you spread your weight more evenly across the surface? You lean to the side and bring your legs up. You reach out towards the edge of the quicksand – you can now see the difference in colour of the dry ground – all the while trying to keep the backpack out of the sand as much as possible. You’re floating! It’s quite easy to move to the side, even with your heavy backpack weighing you down.
You haul yourself out of the quicksand, quickly fling off your wet clothes and wrap yourself in the blanket, jogging on the spot to keep warm. When you’re fairly dry, you step carefully around the quicksand to get water from the well.
With your bottles full of precious water, you set off. A cloud scuds across the moon, dimming your view of the desert. Then another. The wind starts to pick up – you can hear it howling as it scours the dry earth.
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Click here to find out more about quicksand.
Quicksand
It would have been a better idea to have taken off your heavy backpack, but quicksand isn’t as dangerous as you might have thought.
• Quicksand is simply very wet sand, clay or silt. It can’t suck you down (despite the myths about bottomless pits of doom).
• It looks just like ordinary sand, apart from the difference in colour if the surrounding sand is dry, so it’s easy to wander into it by accident.
• It’s quite rare for quicksand to be deep enough that you can’t reach the bottom.
• If you find yourself in quicksand, remove heavy objects and float across the surface to the side. Don’t remain upright.
• Quicksand is usually made by underground springs pushing water upwards into sand or silt – here, it’s the spring that feeds the well.
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As you lick your parched lips, you realise that you should have slowed down well before now. In the desert, your main priority should be making sure you have enough water for the amount of work you’re doing. You die of dehydration after a few days.
The end.
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Click here for tips on how to keep hydrated.
Keeping Hydrated
• If you live in a temperate climate, you will probably be surprised at how quickly you can become dehydrated in a desert.
• If you’re lost in the desert, don’t walk during the day because you don’t know where your next water source might be.
• Don’t run at any time, unless you absolutely have to (for example, if you’re being pursued by an angry baboon).
• We lose most water from sweating. If you’re very hot and suddenly stop sweating, you have heat stroke and need medical attention immediately.
• During the Second World War, the US army had a theory that soldiers could be trained to make do with less water, by gradually reducing their water supplies each day. It didn’t work and caused hundreds of sick, dehydrated soldiers.
• Don’t eat, because water is used up digesting food – you need it for cooling you down more than you need the food.
• Don’t rely on thirst as a guide to your water requirements. Remember that the early stages of dehydration don’t have any symptoms, and even mild dehydration can limit how well your body works.
• Dehydration also reduces concentration and alertness, which you’re probably going to need in a survival situation.
• If your pee is dark in colour, you’re already dehydrated and need to drink.
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You head for the rocks in the half-light. As you climb them, the sun starts to sink over the horizon and the sky darkens even more.
You decide to climb as high as you can to get a good view before the light goes completely . . . however, this close to the equator, there isn’t much of a twilight – darkness falls quickly, taking you by surprise. You’ve made a big mistake in climbing up here, especially without any kind of climbing gear or safety equipment.
You didn’t really think this one through, did you? You get a fantastic view of the setting sun, but as darkness descends you slip on some loose rocks and fall to your death. Look on the bright side: at least your last memory is of a beautiful sunset.
The end.
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You find some rocks that look as though they might be a good place to rest during the day. You have a look around, trying to work out the best place to lay your blanket, where it will be shielded from the sun, when suddenly you are faced with one of the most hideous looking creatures you have ever seen . . .
It looks like some sort of weird spider, hairy and about ten centimetres long, with a huge head and hideous, over-sized jaws. Surely something this horrible has got to be venomous? It scuttles away from you at a surprising speed – faster than any spider – making you shudder.
If you decide to stay at these rocks, but keep away from the nasty-looking creature, which is obviously afraid of you, click here.
If you decide to run away and find somewhere else to rest for the day, click here.
The moon slips behind a cloud. You feel that there’s a change in the air – the cold night feels slightly warmer. You sniff the air, and there is a dampness to it. Surely it’s not going to rain in the Sahara Desert? If it is, then maybe finding water wasn’t such a necessity after all.
The first fat drops of rain begin to fall. There’s a wadi not far away, which looks nice and flat and easy to walk along. Or should you walk along the lower slopes of a mountainside to your right?
If you decide to walk along the high ground, click here.
If you decide to walk along the wadi, click here.
Click here to find out more about rain in the desert.
Rain in the Desert
• You might have thought that the whole point about deserts is the lack of rain. It is true that a desert is de
fined by its low annual rainfall, less than 250 millimetres. But deserts do get some rain – even in the Sahara.
• ‘Average’ rainfall isn’t very useful if you want to know whether or not it’s likely to rain in a desert, because the amount of rainfall is so erratic from year to year. One year an area might have 400 millimetres of rainfall, 300 millimetres the next, and none at all the following year. The average is still below 250 millimetres.
• The low rainfall means that plants and animals have had to adapt to the arid conditions (see here). The resurrection plant is one of the most incredible. When it’s dry, it blows about the desert like tumbleweed, brown and desiccated and dead-looking. But if it finds water it quickly absorbs it and unfurls its leaves. Then it waits for rain to fall. If it does, its seeds fall, germinate and produce shoots on the wet ground in a matter of hours. The plant can remain in its dried out state for a hundred years, and still come back to life when it finds water.
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You wriggle out of the backpack and fling it to the side. It slips on the edge, and gradually falls back into the quicksand. It’s floating on the surface, but you can see it’s starting to sink. Oh no! With a great squelch, you lunge for it – and to your surprise you discover that you can float on the quicksand. You reach the backpack, push it up onto solid ground, then clamber out yourself.
Lost... in the Desert of Dread Page 4