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72 Articles

Welcome to HOW IT WORKS BOOK OF INCREDIBLE EARTH

The planet we live on is a remarkable place, with incredible things happening everywhere, all the time. But have you ever wondered how or why these things occur? How the Earth was created? How we predict the weather? How fossils form? What causes earthquakes? Which animals glow in the dark? Or how the Galapagos Islands came to be? The How It Works Book of Incredible Earth provides answers to all these questions and more as it takes you on a thrilling journey through everything you need to know about the world we live in. Covering the scientific explanations behind weather phenomena, plant life, extreme landscapes and volatile volcanoes, as well as the amazing creatures found throughout the animal kingdom, there is something for everyone to learn about and enjoy. Packed…

Welcome to HOW IT WORKS BOOK OF INCREDIBLE EARTH

NCREDIBLE STORY OF EARTH

Today, science has revealed much about our planet, from how it formed and has evolved over billions of years through to its current position in the universe. Indeed, right now we have a clearer picture of Earth than ever before. And what a terrifying and improbable picture it is. A massive spherical body of metal, rock, liquid and gas suspended perilously within a vast void by an invisible, binding force. It is a body that rotates continuously, is tilted on an axis by 23 degrees and orbits once every 365.256 solar days around a flaming ball of hydrogen 150 million kilometres (93 million miles) away. It is a celestial object that, on face value, is mind-bendingly unlikely. As a result, the truth about our planet and its history eluded humans for thousands…

NCREDIBLE STORY OF EARTH

Supercontinent developmen

Formation of land and sea Current scientific evidence suggests that the formation of liquid on Earth was, not surprisingly, a complex process. Indeed, when you consider the epic volcanic conditions of the young Earth through the Hadean eon, it’s difficult to imagine exactly how the planet developed to the extent where today 70 per cent of its surface is covered with water. The answer lies in a variety of contributory processes, though three can be highlighted as pivotal. The first of these was a drop in temperature throughout the late-Hadean and Archean eons. This cooling caused outgassed volatile substances to form an atmosphere around the planet – see the opposite boxout for more details – with sufficient pressure for retaining liquids. This outgassing also transferred a large quantity of water that was…

Supercontinent developmen

50 AMAZING FACTS ABOUT THE WEATHER

We like to be able to control everything, but weather – those changes in the Earth’s atmosphere that spell out rain, snow, wind, heat, cold and more – is one of those things that is just beyond our power. Maybe that’s why a cloudless sunny day or a spectacular display of lightning both have the ability to delight us. Meteorologists have come a long way in their capability to predict weather patterns, track changes and forecast what we can expect to see when we leave our homes each day. But they’re not always right. It’s not their fault; we still don’t completely understand all of the processes that contribute to changes in the weather. Here’s what we do know: all weather starts with contrasts in air temperature and moisture in the…

50 AMAZING FACTS ABOUT THE WEATHER

Where does acid rain come from?

Acid rain in action Oxidation of sulphur and nitrogen KEY: Blue: Nitrogen Yellow: Sulphur Red: Oxygen All rainwater is a little bit acidic, because the carbon dioxide present in the atmosphere dissolves in water and forms carbonic acid. Stronger acid rain, however, can damage stone structures and can also be harmful to crops, as well as polluting waterways. It forms in the atmosphere when poisonous gases emitted by human activities combine with the moisture within rain clouds. Fossil-fuelled power stations and petrol/diesel vehicles give off chemical pollutants – mainly sulphur dioxide (SO2) and nitrogen oxides (NOx) – which when mixed with the water in the air react and turn acidic.…

Where does acid rain come from?

The smell of rain

It’s possible to smell rain before it has even fallen. Lightning has the power to split atmospheric nitrogen and oxygen molecules into individual atoms. These atoms react to form nitric oxide, which in turn can interact with other chemicals to form ozone – the aroma of which is a bit like chlorine and a specific smell we associate with rain. When the scent carries on the wind, we can predict the rain before it falls. Another smell associated with rain is petrichor – a term coined by a couple of Australian scientists in the mid-Sixties. After a dry spell of weather, the first rain that falls brings with it a very particular aroma that is the same no matter where you are. Two chemicals are responsible for the production of this…

The smell of rain

Global wind patterns

Winds in our atmosphere do not travel in straight lines due to a phenomena known as the Coriolis effect. As the Earth spins on its axis, the motion deflects the air above it. The planet’s rotation is faster at the equator, because this is where the Earth is widest. This difference in speed causes the deflection – for example, if you were to throw a ball from the equator to the North Pole it would appear to curve off-course. If Earth didn’t spin like this, air on the planet would simply circulate back and forth between the high-pressure poles and the low-pressure equator. When the rotation of the Earth is added into the mix, it causes the air in the Northern Hemisphere to be deflected to the right, and air in…

Global wind patterns

La Niña explained

La Niña is defined by unusually cold ocean temperatures in the equatorial Pacific. It’s caused by a build-up of very cool water in the tropical Pacific, which is brought to the surface by easterly trade winds and ocean currents. This upsurge of water causes sea-surface temperatures in areas near South America to drop drastically. La Niña can trigger changes in rainfall patterns, atmospheric circulation and atmospheric pressure, having dramatic effects on the global climate. La Niña events are associated with cataclysmic flooding in Northern Australia. In 2010, they resulted in the worst flooding in Queensland’s history, causing more than two billion Australian dollars’ worth of damage and requiring the evacuation of over 10,000 people. La Niña does have some positive effects, however, often boosting the South American fishing industry due to…

La Niña explained

What are jumping sundogs?

DID YOU KNOW? A single millimetre of soil can take hundreds of years to form in dry climates If you’ve ever seen what appear to be three bright Suns lined up neatly on the horizon, then you’ve probably witnessed the phenomenon knows as sundogs. This rare weather phenomenon occurs when hexagonal ice crystals in the air align to refract sunlight into your eye at a precise angle. This then forms a halo of light around the Sun, with two bright patches on either side of it called parhelia, or sundogs. Even rarer are jumping sundogs, which occur when lightning discharge in a thundercloud temporarily changes the electric field above it. This adjusts the orientation of the ice crystals so that they refract the sunlight differently, making the sundogs move around as if…

What are jumping sundogs?

Why cities are hotter than the countryside

It’s not just busy public transport that makes city life feel sweatier than rural areas. On average, densely populated cities are one to three degrees Celsius (1.8 to 5.4 degrees Fahrenheit) warmer than their surroundings, resulting in a phenomenon known as the urban heat island effect. Dark surfaces of urban buildings and asphalt roads absorb lots of sunlight during the day. The stored energy is given off as heat, warming the area by as much as 12 degrees Celsius (22 degrees Fahrenheit). Another contributing factor is that cities have less vegetation than the countryside, meaning plants can’t help to cool the air by using the excess heat to evaporate the water they absorb. The use of cars and air conditioning also increases temperatures of cities.…

Why cities are hotter than the countryside

How do jet streams work?

DID YOU KNOW? Mount Everest is so high that its 8,848m (29,029ft) summit actually sits in a jet stream Jet streams are currents of fast-moving air found high in the atmosphere of some planets. Here on Earth, when we refer to ‘the jet stream’, we’re typically talking about either of the polar jet streams. There are also weaker, subtropical jet streams higher up in the atmosphere, but their altitude means they have less of an effect on commercial air traffic and the weather systems in more populated areas. The northern jet stream travels at about 161-322 kilometres (100-200 miles) per hour from west to east, ten kilometres (six miles) above the surface in a region of the atmosphere known as the tropopause (the border between the troposphere and the stratosphere). It’s created…

How do jet streams work?

The sulphur cycle

The sulphur cycle is one of many biochemical processes where a chemical element or compound moves through the biotic and abiotic compartments of the Earth, changing its chemical form along the way. As with both the carbon and nitrogen cycles, sulphur moves between the biosphere, atmosphere, hydrosphere and lithosphere (the rigid outer layer of the Earth). In biology, the water, oxygen, nitrogen, carbon, phosphorus and sulphur cycles are of particular interest because they are integral to the cycle of life. Sulphur, which is present in the amino acids cysteine and methionine as well as the vitamin thiamine, is a vital part of all organic material. Plants acquire their supply from microorganisms in the soil and water, which convert it into usable organic forms. Animals acquire sulphur by consuming plants and one…

The sulphur cycle

Cut off from the Sun, rain and wind that we experience on the surface, you might assume meteorological conditions in caves never change. However, the reality is that their climates do vary significantly – not only from location to location, but within individual caves over time. Indeed, some examples, like the Er Wang Dong cave system in Chongqing Province, China (main picture), even host their own weather. Ultimately this is because very few caves are 100 per cent cut off from their surroundings. In the case of Er Wang Dong, it all comes down to an imbalance in the local topology. There are several tunnels around the cave system’s perimeter where wind can blow in. Once trapped underground air from outside gains moisture, pooling into huge chambers like Cloud Ladder Hall…

Predicting the weather

The weather affects us all, every day. From governing the difference between life and death, to providing a conversation topic to fill awkward silences at a party, it is an ever-present and ever-changing part of life. This means that predicting it accurately is a hugely important task. In the UK, the Met Office is responsible for weather monitoring and prediction. Before a forecast can be put together, measurements from thousands of data recorders across the world are collected and analysed. Every day, around 500,000 observations are received, including atmospheric measurements from land and sea, satellites, weather balloons and aircraft. But, this is still not enough to represent the weather in every location. To fill in the gaps, the data is assimilated. This combines current data with what is expected, to provide the…

Predicting the weather

Lightning occurs when a region of cloud attains an excess electrical charge, either positive or negative, that is powerful enough to break down the resistance of the surrounding air. This process is typically initiated by a preliminary breakdown within the cloud between its high top region of positive charge, large central region of negative charge and its smaller lower region of positive charge. The different charges in the cloud are created when water droplets are supercooled within it to freezing temperatures and then collide with ice crystals. This process causes a slight positive charge to be transferred to the smaller ice crystal particles and a negative one to the larger ice-water mixture, with the former rising to the top on updrafts and the latter falling to the bottom under the effect…

Lightning types

Bead lightning A type of cloud-to-ground lightning where the strike seems to break up into smaller, super-bright sections (the beads), lasting longer than a standard discharge channel. Frequency: Rare Ribbon lightning Only occurring in storms with high cross winds and multiple return strokes, ribbon lightning occurs when each subsequent stroke is blown to the side of the last, causing a visual ribbon effect. Frequency: Quite rare Staccato lightning A heavily branched cloud-to-ground lightning strike with short duration stroke and incredibly bright flash. Frequency: Common Sheet lightning A generic term used to describe types of cloud-to-cloud lightning where the discharge path of the strike is hidden from view, causing a diffuse brightening of the surrounding clouds in a sheet of light. Frequency: Common Megalightning A term commonly used when referring to upperatmospheric types of lightning. These include sprites, blue jets and elves (see ‘Atmospheric…

Lightning types

What are the chances?

1 in 300,000 The chance of you getting struck by lightning is one in 300,000. Which, while seeming quite unlikely, did not stop US park ranger Roy Sullivan from being struck a world record seven times during his lifetime. in comparison… 1 in 14,000,000 The chance of winning the lottery in the UK is one in 14 million. That is over 45 times as unlikely as being struck. 1 in 11,000,000 Flying on a single-trip commercial air flight inflicts you to a one in 11 million chance of being killed in an accident. 1 in 12,000,000 The odds of getting hit by lightning are 40 times more likely than the chance of dying from Mad Cow Disease in the UK. 1 in 8,000 In order to get better odds, go out in your car. Over 3,000…

What are the chances?

What happens when you get struck by lightning?

When a human is hit by lightning, part of the strike’s charge flows over the skin – referred to as external flashover – and part of it goes through them internally. The more of the strike that flows through, the more internal damage it causes. The most common organ affected is the heart, with the majority of people who die from a strike doing so from cardiac arrest. Deep tissue destruction along the current path can also occur, most notably at the entrance and exit points of the strike on the body. Lightning also causes its victims to physically jump, which is caused by the charge contracting the muscles in the body instantaneously. Burns are the most visible effect of being struck by lightning, with the electrical charge heating up any…

What happens when you get struck by lightning?

Firestorms are among nature’s most violent and unpredictable phenomena. Tornado-force winds sweep superhot flames of up to 1,000 degrees Celsius (1,800 degrees Fahrenheit) through buildings and forests alike. Victims often suffocate before they can flee and entire towns can be obliterated. Survivors of firestorms describe darkness, 100-metre (330-foot)-high fireballs and a roaring like a jumbo jet. To give you an idea of the sheer heat, firestorms can be hot enough to melt aluminium and tarmac, warp copper and even turn sand into glass. Firestorms happen worldwide, especially in the forests of the United States and Indonesia, and in the Australian bush. They occur mostly in summer and autumn when vegetation is tinder dry. Although they are a natural phenomenon, among the most devastating were triggered deliberately. During World War II, for…

How plants work

Truly, it’s not easy being green. But plants not only survive, they thrive all over the globe, without the benefit of muscles, brains or personalities. It’s a good thing they do: plants head up nearly all food chains, pump out the oxygen we breathe, hold off erosion and filter pollutants out of the atmosphere. Over the past 3.5 billion years, they’ve diversified into an estimated 320,000-430,000 separate species, with more coming to light every year. All this stems from one neat trick: harnessing the Sun’s energy to power a built-in food factory. Through this process, called photosynthesis, plants combine carbon dioxide with water to create carbohydrates that they use to grow and reproduce. The earliest plants, similar to today’s algae, didn’t do much other than photosynthesise. They floated around in the…

How plants work

See the leaves for the trees

Oak There are two main types of oak tree, the sessile oak and the pedunculate oak (which has a shorter stem). Oak leaves are used by the US Army as a rank symbol. Maple You might recognise this leaf from Canada’s national flag. A maple tree’s leaves usually have between three and nine lobes, and are arranged opposite one another on the branches. Ash Ash leaves form in pairs; each central stem will bear nine to 13 leaflet pairs with one leaf at the tip. All leaves are pointed and toothed, and have tiny hairs on their lower surface. Plantain These form in a rosette formation and range from five to thirty centimetres (two to 12 inches) in length. Generally, they are egg-shaped and are often hairless. Willow Willow leaves tend to be long and thin and will alternate…

See the leaves for the trees

Why do flowers smell?

The role of scent This lily has been picked apart to show the different structures that ensure pollination Flowers have just one biological role: to guarantee pollination. Many blooms are pollinated by insects, attracted by a flower’s bright colours and the reward of energy-rich pollen or nectar. But flowers must also lure insects from much farther afield – enter, scent. The aroma of some flowers contains up to 100 different chemicals. These are modified from chemicals in leaves which deter grazing animals, but are manufactured within the flower. Warm weather stimulates their release – just when bugs are most active Characteristic scents encourage insects to visit other flowers of the same species and so transfer pollen between them. The blooms of evening primrose and night-scented stock release their sweet aroma in the evening, attracting…

Why do flowers smell?

What are orchids?

With 25,000 species, the orchid is the largest of the planet’s plant families with the most diverse species growing in the tropics and subtropics. Orchids are found on all continents but Antarctica and can survive pretty much anywhere except true deserts and open water. Orchids grow on the ground using subterranean roots, though some have also developed the ability to grow up trees and other structures using aerial roots. What sets an orchid apart from most flowering plants, however, is its reproductive anatomy. Orchids have three petals (including one colourful lower petal called the labellum) and three sepals. While on other plants male and female reproductive organs remain separate, on an orchid these parts are fused in a central column.…

What are orchids?

Why is poison ivy so irritating?

Poison ivy is a plant with leaves that divide into three leaflets and often displays yellow or white berries or small white flowers. The glossy leaves, roots and stem of the plant contain an oily, organic toxin called urushiol, to which nine out of ten people are allergic. If they come into contact with this chemical their bodies overreact, causing a skin irritation known as urushiolinduced contact dermatitis. Thinking it’s under attack, the body tells the immune system to take action against the foreign urushiol substance. The resulting allergic (anaphylactic) reaction produces irritation in the form of redness, rashes and itchy skin.…

Why is poison ivy so irritating?

The life of trees

When you look at a tiny acorn on the forest floor, it’s difficult to imagine just how much potential that little seed contains. If it germinates, after around 50 years it will have grown into a towering oak tree, with the capacity to outlast generations of humans. And that’s just one tiny acorn. Scientists have estimated that there are around 3 trillion trees on our planet, belonging to around 100,000 different species. Each of these trees contributes to regulating our climate and producing air for us to breathe, as well as many more important roles that may surprise you. DID YOU KNOW? ‘Pando’ is a colony of quaking aspen trees in Utah, which has a single root mass and is around 80,000 years old…

The life of trees

Woodland wildlife

From leaves to bark and everything in between, every inch of woodland is useful to one critter or another. Large populations of trees create many varied habitats, from pine forests to wet woodlands, each with different ecological properties and a unique wildlife population. In summer, when a tree’s leaves are in full bloom, the dense foliage of the woodland canopy absorbs the Sun’s energy, providing shade and regulating the woodland’s climate. Similarly, in the winter months, the dense network of leaves and branches are an effective barrier against pouring rain and howling wind, sheltering the animals within. Green leaves, buds, fruit and bark provide food for many animals, such as squirrels, deer and birds. A tree’s branches make handy perches for feasting upon, or a perfect vantage point to lie in wait…

Woodland wildlife

The importance of trees

DID YOU KNOW? It is estimated that all of the world’s forests combined absorb 8.8 billion tons of carbon dioxide per year Trees are the lungs of our planet. As a key part of the carbon cycle, when trees photosynthesise to make their own food, they take in carbon dioxide and convert it to release oxygen, storing the rest of the carbon that gets decomposed into the soil when the tree dies. When a whole forest does this, the intake of CO2 is huge. With rising CO2 levels in our atmosphere being an important factor in climate change, the work of trees becomes all the more prominent. It’s estimated that our planet’s trees absorb up to 40 per cent of the carbon dioxide created by humans each year. When the trees are…

The importance of trees

How do cacti live?

Cacti are hardy, flowering plants in the caryophyllales order that have evolved to survive in some of the Earth’s driest and most barren landscapes. This unceasing survival is achieved through the specialised tailoring of two main principles: form and function. First, all cacti have developed optimal forms for retention of internal water supplies (spheres and cylinders), combining the highest possible volume for storage with the lowest possible surface area for loss. This allows cacti to store vast quantities of water for elongated periods – for example, the species Carnegiea gigantea can absorb 3,000 litres in a mere ten days. This ability directly correlates to the typical weather patterns of Earth’s barren, dry environments, where cacti are predominantly found, with little water being deposited for months on end, only for a short…

How do cacti live?

How are plants cloned?

DID YOU KNOW? The first commercially cloned animal was a cat, Little Nicky. Born in 2004, it cost its owner £30,000 ($50,000) The process of cloning plants has been used in agriculture for centuries, as communities split roots and took cuttings to efficiently create multiple plants. Taking a cutting from near the top of a plant, placing it in moist soil and covering it will enable a new offspring to grow with the same genetic code as the parent from which it was taken. This method of cloning is very easy to do and is common among casual gardeners and industrial farmers alike. However, in more recent years the cloning of plants has made its way into the laboratory. Responsible for that shift is German physiologist Gottlieb Haberlandt who was the first to…

How are plants cloned?

How do plants grow towards light?

Phototropism With the help of the hormone auxin, plants can get as much light as possible Plants depend on a process called photosynthesis to make their own food. This process converts water from the soil and carbon dioxide in the air into oxygen and glucose (sugar). Sunlight is crucial for this chemical change and without it, green plants are unable to survive. Plant cells contain a protein called phototropin, which is activated when it absorbs the blue wavelength of light. This leads to an uneven distribution of the hormone auxin (which regulates growth) in the stem. The exact mechanisms behind this process are not fully understood, but one theory is that sunlight destroys or inhibits auxin so the hormone levels on the Sun-facing side reduce. Another theory is that auxin molecules are able…

How do plants grow towards light?

Drosera There are over 100 species of drosera, which are commonly known as ‘sundews’ as they appear to be constantly covered in dew. These tiny droplets are actually sticky enzymes that trap and start to digest prey as soon as it lands on the plants’ leaves. Venus flytrap When an insect or arachnid steps on more than one of the tiny hairs of the plant’s jaws, it triggers a violent reaction. The hinged mouth snaps down, trapping the prey inside the plant. Digestive enzymes are secreted and it can be several days until the plant re-opens. Nepenthes These plants lure insects, and sometimes even rats, into their cup-like pitchers with an attractive scent. Once trapped, the prey drowns in the liquid within the pitcher and is broken down by digestive juices, allowing the plant to…

DID YOU KNOW? Ancient Ethiopians are credited as first recognising the energising effect of the coffee plant Coffee production starts with the plantation of a species of coffee plant, such as the arabica species. Plants are evenly spaced at a set distance to ensure optimal growing conditions (access to light, access to soil nutrients, space to expand). Roughly four years after planting, the coffee plant flowers. These flowers last just a couple of days, but signal the start of the plant’s berry-growing process. Roughly eight months after flowering, the plant’s berries ripen. This is indicated by the change in shade, beginning a dark-green colour before changing through yellow to a dark-red. Once dark-red, the berries are then harvested by strip picking or selective picking. The former is an often mechanised technique where…

SURVIVING EXTREME EARTH

For many of us, the toughest conditions we’d ever have to face would probably be walking the dog in the bucketing rain. However, outside of the urban sprawl there are some places on Earth that aren’t so hospitable to humans. While mankind has successfully populated large areas of the planet’s land surface, there are still many places you wouldn’t dare to venture unless you really enjoy a challenge or have just got horribly, horribly lost. History is littered with people who have faced the biggest tests this planet has to offer, whether deliberately or accidentally, and lived to tell the tale, but many have fallen victim to frozen wastes or scorching plains. Even the best-prepared adventurers can come unstuck in the face of the amazing force of nature. Over the next few…

SURVIVING EXTREME EARTH

Waterfall wonders

Big waterfalls are among the most spectacular geological features on Earth. The thundering waters of Niagara Falls can fill an Olympic-sized pool every second. Visitors are drenched with spray and deafened by volumes reaching 100 decibels, equivalent to a rock concert. A waterfall is simply a river or stream flowing down a cliff or rock steps. They commonly form when rivers flow downhill from hard to softer bedrock. The weak rock erodes faster, steepening the slope until a waterfall forms. The Iguazú Falls on the Argentina-Brazil border, for example, tumble over three layers of old resistant lava onto soft sedimentary rocks. Any process that increases the gradient can generate waterfalls. A 1999 earthquake in Taiwan thrust up rock slabs along a fault in the Earth’s crust, creating sharp drops along several rivers…

Waterfall wonders

The jagged maze of Tsingy de Bemaraha

Carving a stone forest Water is the architect of this ruthless rocky environment “The Tsingy is an incredible feat of natural sculpting” From above, the formidable jagged pinnacles of the Tsingy de Bemaraha look like a stone forest. Found on the west coast of Madagascar, it is an incredible feat of natural sculpting. The rock formations are a karst system – a geological term used when a landscape is made up of soluble rock, such as limestone, that is scoured away and dissolved over time by the flow of water. About 2 million years ago, the area was a lagoon, beneath which lay a deep bed of limestone. Over millennia, tectonic activity and falling sea levels caused this rock to be elevated above the water, exposing the soft limestone rock to the elements. On…

The jagged maze of Tsingy de Bemaraha

Antarctica explored

Antarctica is the world’s last great wilderness and Earth’s coldest, windiest, highest and driest continent. Around 98% of the land area lies buried beneath kilometres of snow and ice, yet Antarctica is – paradoxically – a desert. In fact, it is so inhospitable that no one lives there permanently, despite it being 25% bigger than Europe. This frozen continent remained unexplored until the 19th century. Unveiling its mysteries claimed many lives. Antarctica is definitely worth a visit from your armchair, however, because it may also be Earth’s quirkiest and most remarkable continent. Among its marvels is a river that flows inland, Mars-like valleys where NASA scientists test equipment for space missions, and perpetually dark lakes where bacteria may have survived unchanged since Antarctica had lush forests like the Brazilian rainforest. Living…

Antarctica explored

An alien landscape on Earth

“It looks as though it belongs on another planet, with green pools of acid and toxic gases spewing from the surface” DID YOU KNOW? Dallol is located in the Danakil Depression, one of the lowest areas on Earth, at 125m (410ft) below sea level If a ticket to Mars is a little out of your price range, then a visit to Dallol in Ethiopia might be the next best thing. The colourful landscape looks as though it belongs on another planet, with green pools of acid, strange salt formations and toxic gases spewing from the surface. The area is actually a large volcanic crater, formed when rising basaltic magma made contact with salt deposits and ground water. This caused the water to evaporate immediately, resulting in a huge eruption of rock, ash, water…

An alien landscape on Earth

Glaciers are huge rivers or sheets of ice, which have sculpted mountain ranges and carved iconic peaks like the pyramid-shaped Matterhorn in the Swiss Alps. The secret of this awesome landscape-shaping power is erosion, the process of wearing away and transporting solid rock. Glacial erosion involves two main mechanisms: abrasion and plucking. As glaciers flow downhill, they use debris that’s frozen into the ice to ‘sandpaper’ exposed rock, leaving grooves called ‘striations’. This is the process of abrasion. Plucking, however, is where glaciers freeze onto rock and tear away loose fragments as they pull away. Today glaciers are confined to high altitudes and latitudes, but during the ice ages glaciers advanced into valleys that are now free of ice. Britain, for example, was covered by ice as far south as the…

Wonders of YELLOWSTONE PARK

DID YOU KNOW? There are more people injured by bison than grizzly bears each year in eYllowstone Welcome to Yellowstone Park – America’s, and the world’s, very first national park. Its vast swath of 9,000 square kilometres (3,500 square miles) of protected land, which spans the borders of Wyoming, Montana and Idaho, could house all five boroughs of New York City ten times over, and attracts over 3 million visitors each year. Its world-renowned scenery includes soaring peaks, plunging canyons, lush forests, rushing rivers, brilliant lakes, rolling meadows, thundering waterfalls, shimmering hot springs and gushing geysers. Amid all this visual poetry lives a rich assortment of wildlife, including wolves, bears, bison and elk. Yellowstone National Park was established by US Congress in 1872, soon after the first Europeans arrived in the American West,…

Wonders of YELLOWSTONE PARK

DID YOU KNOW? The ocean appears blue because it reflects short wavelengths of light (such as blue) and absorbs longer ones New South Wales, AustraliaTasman Sea / South Pacific 1 Most sharkinfested Just like Jaws, only less cinematic trickery and more lose-a-leg scary When it comes to shark attacks, there are three species that sit firmly at the top of the food chain: the great white shark, the tiger shark and the bull shark. This is one gnarly trio of hungry fish, who are all keen predators with heightened senses. The most extreme place on Earth for shark attacks recently is New South Wales coast in Australia and over the last year the country has seen two fatalities, 29 attacks and 18 injuries. It’s thought that changing ocean currents are bringing the sharks’ prey closer…

The phosphorus cycle

How phosphorus is recycled Discover where this prolific element comes from and the various states that it goes through… Key: Man-made phosphorus Natural phosphorus Phosphorus is a crucial element to life, whether an organism is a member of the plant or animal kingdom. It forms a fundamental component of genes – the DNA and RNA structure that determines what we are – and it also plays a major role in the ATP (adenosine triphosphate) energy cycle, without which we wouldn’t be able to contract our muscles. In vertebrates like us mammals, around 85 per cent of the phosphorus in our bodies can be found in our teeth and bones. Phosphorus goes through a cycle similar to that of carbon, nitrogen and sulphur. However, unlike these important systems, because of the Earth’s normal range of…

The phosphorus cycle

Petrified forests

All over the world you can find very strange-looking slabs of wood, strewn across a barren landscape. However, these haven’t actually been wooden for millions of years. Around 225 million years ago, prehistoric trees fell into rivers, where they were quickly covered with a layer of sediment, silt and mud. This rapidly formed a tight wrap around the trunk, cutting off any oxygen that would have rotted the wood. Over time, minerals were absorbed into the wood, including silica. This material is known for its crystallising properties and as the log slowly rotted away over a period of many centuries, the silica replaced it, forming stunning crystal representations of the original material’s shape and turning the wooden logs into quartz slabs. As the floods washed or evaporated away, they left these quartz…

Petrified forests

The lithosphere

How did continents form? The lithosphere has been around since the formation of the Earth, but it has been hypothesised that all land was once joined together. This supercontinent is called Pangaea, Greek for ‘all lands.’ The theory goes that as the tectonic plates split apart, they pulled the various landmasses with them, forming the continents we know today. If you look closely, South America and Africa fit together well, with North America slotting neatly into the middle. Further evidence for Pangaea comes in the form of fossils found in both Africa and South America. The animals that formed the fossils are unlikely to have lived in both continents unless they were once conjoined. Cutting through the Earth What would the Earth would look like if you sliced a 100km (62mi) section out of…

The lithosphere

SUPER VOLCANOES

Inside a supervolcano Many people will remember the airport chaos of spring 2010 when Eyjafjallajökull, one of Iceland’s largest volcanoes, erupted after almost two centuries of peaceful slumber. But though it might be hard to believe, considering the mammoth amount of disruption that it caused, the Icelandic eruption was tiny compared to a super-eruption’s devastating power. The Eyjafjallajökull event measured a mere 4 on the Volcanic Explosivity Index (VEI), which rates the power of eruptions on an eight-point scale. A massive VEI 8 blast, on the other hand, would threaten human civilisation. Such a super-eruption would spew out more than 1,000 cubic kilometres (240 cubic miles) of ejecta – ash, gas and pumice – within days, destroying food crops, and changing the world climate for years. A super-eruption hasn’t happened in recorded history,…

SUPER VOLCANOES

From magma to lava Beneath the Earth flows molten rock known as magma. When a volcano erupts, the resulting explosion shoots this magma out into the atmosphere. At this point the magma becomes known as lava. There is no major difference between magma and lava; the terms merely distinguish whether the molten rock is beneath or above the surface. Caused by gas pressure under the surface of the Earth, a giant volcanic eruption can be incredibly powerful with lava shooting up to 600 metres (2,000 feet) into the air. Lava can reach temperatures of 700-1,200°C (1,300-2,200°F) and varies in colour from bright orange to brownish red, hottest to coldest, respectively. This viscous liquid can range from the consistency of syrup to extremely stiff, with little or no flow apparent. This is regulated…

The eruption of Mount St Helens

Mount St Helens blew off its summit in May 1980 with the energy of 20,000 Hiroshima-size atomic bombs. The resulting rock blast and mudslides killed 57 people and around 7,000 large animals, engulfed 200 houses, choked rivers, buried highways and flattened trees like matchsticks. Ash closed nearby airports for up to two weeks, grounding thousands of flights. The damage cost $1.1 billion to repair. The volcano remains active to this day and it’s America’s second-most dangerous volcano. It sits on the Ring of Fire – a 40,000-kilometre (25,000-mile) horseshoe of volcanoes circling the Pacific Ocean. Beneath Mount St Helens, two of the massive rock plates that form the Earth’s crust are colliding; the oceanic Juan de Fuca Plate is sliding beneath the continental North American Plate. As the ocean plate grinds…

The eruption of Mount St Helens

Earthquakes are one of our planet’s most destructive natural hazards, with the ability to flatten entire cities, trigger enormous tsunamis that wash away everything in their path, and cause a devastating loss of life. Part of an earthquake’s immense power lies in its unpredictability, as a huge quake can strike with very little warning, giving those nearby no time to get to safety. Though we don’t know when they will occur, we can predict where, thanks to our knowledge of plate tectonics. The thin top layer of the Earth, known as the crust, is divided into several plates that are constantly moving. This is caused by heat from the core of the Earth creating convection currents in the mantle just below the crust, which shifts the plates in different directions. As the plates…

Anatomy of an earthquake

Earthquakes are caused by the build-up of pressure that is created when tectonic plates collide. Eventually the plates slip past each other and a huge amount of energy is released, sending seismic waves through the ground. The point at which the fracture occurs is often several kilometres underground and is known as the focus or hypocentre. The point directly above it on the surface is the epicentre, and this is where most of the damage is caused. Earthquakes have different characteristics depending on their type of fault line, but when they occur underwater, they can sometimes trigger enormous destructive waves called tsunamis. Fault lines How the Earth’s crust moves along different plate boundaries 750 kilometres Depth of the deepest earthquakes How earthquakes occur The build-up of pressure that causes the ground to move and shake Earthquake…

Anatomy of an earthquake

Monitoring earthquakes

Earthquakes are measured using an instrument called a seismograph, which produces a visual record of tremors in the Earth’s crust. This shows the seismic waves of the earthquake as a wiggly line, allowing you to plot the different waves types. The small but fast P waves appear first, followed by the larger but slower S waves and surface waves. The amount of time between the arrival of the P and S waves shows how far away the earthquake was, allowing scientists to work out the exact location of the epicentre. The size of the waves also helps them determine the magnitude or size of the earthquake, which is measured using the Richter Scale. How a seismograph works The clever device that records earthquakes as they happen 15tons Weight of the largest spring-pendulum seismometer The…

Monitoring earthquakes

How cenotes form

“The water wears the limestone away to create great cavernous chambers” Found on Mexico’s Yucatán peninsula, a cenote (pronounced ‘say-no-tay’) is effectively a really pretty sinkhole. These colossal underground caverns are filled with deep, crystal-clear water and are used as both swimming and diving spots for tourists and scuba enthusiasts, not to mention being sites of incredible archaeological and cultural significance for the Yucatán’s locals. The Yucatán peninsula is formed of limestone and was once a coral reef, exposed just above sea level during the last ice age. The peninsula doesn’t have many rivers or steams above ground, but below the surface flow the three longest underground water systems in the world. These essential waters have helped civilisation thrive on the Yucatán for thousands of years. Fractures in the limestone bedrock form the…

How cenotes form

Mountain formation

Mountains are massive landforms rising high above the Earth’s surface, caused by one or more geological processes: plate tectonics, volcanic activity and/or erosion. Generally they fall into one of five categories – fold, fault-block, dome, volcanic and plateau – although there can be some overlap. Mountains comprise about 25 per cent of our land mass, with Asia having more than 60 per cent of them. They are home to 12 per cent of the Earth’s population, and they don’t just provide beauty and recreation; more than half of the people on Earth rely on the fresh water that flows down from the mountains to feed streams and rivers. Mountains are also incredibly biodiverse, with unique layers of ecosystems depending on their elevation and climate. One of the most amazing things about mountains…

Mountain formation

The Grand Prismatic Spring

Yellowstone Park, Wyoming, became the world’s first national park when President Ulysses S Grant signed it into law in 1872. It’s not hard to see why the government wanted to preserve this area of great natural beauty, especially with features like this: the world’s third-largest hot spring. The Grand Prismatic Spring is Yellowstone’s largest at 90 metres (295 feet) wide and 50 metres (164 feet) deep, and works like many of the park’s hydrothermal features. Water deep beneath the ground is heated by magma and rises to the surface unhindered by mineral deposits. As it bubbles to the top it cools and then sinks, only to be replaced by hotter water coming from the depths in a continuous cycle. The hot water also dissolves some of the silica in the rhyolite…

The Grand Prismatic Spring

Who opened the Door to Hell?

DID YOU KNOW? The Derweze natural gas field is 260km (162mi) north of Ashgabat, Turkmenistan’s capital city The Derweze natural gas crater is a basin 70 metres (230 feet) across located in the middle of the Karakum Desert in Turkmenistan. The crater, which was created when a natural gas drilling rig and camp collapsed in 1971, is informally referred to by the local people as the ‘Door to Hell’. The flames were instigated when a Soviet Union drilling team decided that, after their rig collapsed, the best way to deal with the large amount of methane gas spilling out into the environment was to burn it off. Geologists at the time predicted that the methane would combust within days, but four decades later the natural gas continues to blaze, lighting up the…

Who opened the Door to Hell?

How do crater lakes form?

When you look out across a mountain lake it can be easy to think it was always so serene, but this couldn’t be further from the truth. From the shifting of Earth’s tectonic plates to glaciers gouging out the land, the majority of these tranquil sites are the result of epic geological events. Crater lakes have the most epic beginnings of all. While maar lakes are also the result of volcanism, forming in fissures left behind by ejected magma, they are generally shallow; Devil Mountain Maar in Alaska is the deepest at just 200 metres (660 feet). Maars aren’t a patch on their bigger cousins. Crater lakes have very violent origins. eruptions, the terrain becomes superhot and highly unstable. In some cases the volcanic activity is so intense that once all…

How do crater lakes form?

Stalagmite and stalactite formation

Struggling to tell the difference between these two formations? When you see the letter ‘c’ in stalactites, think ‘ceiling’, as they hang from the roofs of caves. And when you see the ‘g’ in stalagmites, think ‘ground’, as they rise from the floor like inverted icicles. Both structures are known as speleothems, and are formed over thousands of years, as water trickles through the cave and minerals are deposited layer upon layer. Stalactites Steady drops of water build these structures downwards Stalagmites These formations slowly rise upwards from the cave floor…

Stalagmite and stalactite formation

What is soil made of?

In its simplest form, soil is a gritty mixture of ground-up minerals and decaying organic matter, such as leaf litter from the forest canopy. These raw ingredients are then mixed and churned together by the bugs and worms that live within. The broken-up rocks that make up soil can come from the bedrock that lies deep below, or from other sources, where rocks, rubble and more soil is transported by forces such as rivers or glaciers. There are six major types of soil, each with different mineral quantities and qualities. Clay soils are dense but high in nutrients, sandy soils are light, dry and relatively acidic, while silt soils are very fertile and hold plenty of moisture. Loam soils contain a balance of clay, sandy and silt soil types, while peat soil…

What is soil made of?

How is coal formed?

When will Earth’s coal run out? No one knows exactly when we’ll run out of coal, but its use has skyrocketed during the last 200 years. We used a whopping 6.8 billion tons – that’s the approximate weight of 4 billion cars – in 2009 alone. Around 860 billion tons of coal remains unmined and major coal producers estimate supplies will last around 130 years at current rates. Despite this estimate we can’t be sure that coal won’t run out sooner, as the world’s remaining coal may turn out to be hard to reach or bad quality. Worse still, we’re uncertain how much coal is buried. India, for example, overestimated its coal reserves by 36 billion tons in 2003. Alternatively, we may develop better sources of energy, stop using coal and never…

How is coal formed?

What are fossils?

Types of fossilisation Dependent on climate and ground conditions, deceased animals can be fossilised in many ways Carbon dating A crucial tool for palaeontologists, carbon dating allows ancient fossils to be accurately dated Carbon dating is a method of radioactive dating used by palaeontologists that utilises the radioactive isotope carbon-14 to determine the time since it died and was fossilised. When an organism dies it stops replacing carbon-14, which is present in every carbonaceous organism on Earth, leaving the existing carbon-14 to decay. Carbon-14 has a half-life (the time it takes a decaying object to decrease in radioactivity by 50 per cent) of 5,730 years, so by measuring the decayed levels of carbon-14 in a fossil, its time of death can be extrapolated and its geological age determined. The origin of life on Earth is…

What are fossils?

THE FOSSIL RECORD

1 | QUATERNARY | 2.588-0.00 Ma The most recent period in Earth’s history, the Quaternary is characterised by major changes in climate, as well as the evolution and dispersement of modern humans. Due to the rapid changes in environment and climate (ie ice ages), many larger mammal fossils have been discovered, including those of mammoths and sabre-toothed cats. 2 | NEOGENE | 23.03-2.588 Ma Covering 23 million years, the Neogene period’s fossils show a marked development in mammals and birds, with many hominin remains excavated. The extinct hominid australopithecus afarensis – a common ancestor of the genus homo (that of modern humans) – is one of the most notable fossil finds, as exemplified in the specimens Lucy and Selam. 3 | PALEOGENE | 65.5-23.03 Ma The first period of the Cenozoic era, the Paleogene is…

THE FOSSIL RECORD

Deadly sinkholes

DID YOU KNOW? 24,671 insurance claims for sinkhole damage were registered in Florida between 2006 and 2010 In March 2014, a huge hole suddenly opened up in a road intersection in the city of Detroit in the United States. It was nine metres (30 feet) wide and five metres (16 feet) deep. This is a type of geohazard known as a sinkhole. They are the result of unstable cavities in the ground, which are created from soluble bedrock dissolution caused by a change in underground moisture content and water levels. Because of this, these massive pits more commonly appear in the calendar’s wetter months. The effect is exaggerated even more when sudden flooding follows a drought as the ground is not saturated and cannot handle the unexpected deluge. The most common rocks…

Deadly sinkholes

THE ANIMAL KINGDOM

Sort your life out! A brief guide to how we structure all life on Earth Domain Kingdom Phylum Class Order Family Genus Species What proportion of species belongs to each group? Arthropoda: 83.7% Mollusca: 6.8% Chordata: 3.6% Nematoda: 1.4% Platyhelminthes: 1.4% Annelida: 1.0% Cnidaria: 0.6% Echinodermata: 0.5% Porifera: 0.3% Others: 0.7% In the fourth century BCE, Aristotle divided the world into animals and plants. The word ‘animal’ comes from the Latin animalis and means ‘having breath’. Animals were all the living creatures that moved and breathed, while plants were the ones that stayed put. For over 2,000 years the living world was divided into just these two kingdoms. After the invention of the microscope and later the electron microscope, scientists came to recognise that single-celled organisms couldn’t really be classified as animals or plants. Bacteria and another type of single-celled organism called Archaea are now counted as fundamentally different groups of…

THE ANIMAL KINGDOM

Why do fish have scales?

Thriving underwater requires some excellent morphological adaptations. One key attribute are scales: strong and durable plates that allow for fluid movement and protection from parasites, scrapes and predators. There are many types of scale, depending on the fish’s evolutionary history. For instance, sharks and rays have placoid scales, while ganoid scales are present on sturgeons and paddlefish. The properties of each scale type are suited to the fish’s lifestyle and habitat. The scales all grow in the same direction, tapering towards the tail to make the fish streamlined. Fish with larger, heavier scales such as the Amazonian arapaima gain more protection but are often more restricted in their movement, whereas species such as eels have much smaller and sometimes microscopic scales that give more flexibility, but at the loss of an…

Why do fish have scales?

Amazing animal architects

Humans are not the only species capable of building extraordinary structures. The natural world is full of ingenious animals that can achieve just as impressive feats of engineering. Building behaviour is common in mammals, birds, insects and arachnids. Many animals learn to build by observation and even through communication. However, in some cases building is thought to be instinctive. Animals will often construct their own habitats for shelter against potential predators and the outside elements. Many dwellings are also built for nesting purposes and to catch, store and even cultivate food. Animal architecture can also be quite sophisticated, with many structures incorporating clever ventilation systems for temperature control, and even secure entry and exit points to keep unwanted visitors away. Complex builds are often undertaken as a group, which helps speed up construction…

Amazing animal architects

DID YOU KNOW? A study found that black garden ants build a specific area in their nest for excrement, just like a built-in loo! A single ant is capable of carrying up to 50 times its own weight, so working together as a colony means they’re able to accomplish some seriously impressive feats. In fact, within a week a large army of garden ants can construct an underground city big enough to house thousands of insects. Established deep underground, ant nests are made up of multiple chambers and connecting tunnels. Each chamber has a different use; some store food while others are used as nurseries for the young and resting spaces for busy worker ants. You’ll find the queen ant in the central chamber where she will lay her eggs. Porous turrets are…

Beavers are important engineers in the animal kingdom; their dams create ponds that provide food and protection from harmful predators, benefiting both them and smaller species. To remain warm, dry and safe on the wetland, beavers will also construct lodges. These impressive dwellings are made up of mud, sticks and rock and also feature a ventilation shaft at the top, ensuring fresh air circulates through the hollow internal chamber. The chamber itself is filled with dry bedding and is where the beaver will reside and raise their young. In order to get quick access to food and evade potential predators, beavers will enter and exit the lodge via a water-filled tunnel that leads directly into the surrounding pond. Beaver constructions Inside a beaver’s unique watery habitat “These dwellings are made of mud, sticks and rock…

AMAZING GLOW-IN-THE-DARK ANIMALS

Imagine walking through a forest at night and encountering a swarm of dancing lights floating in the air. It may look like magic, but it is one of the most astounding features of the natural world: bioluminescence. The flying flickers of light are a biochemical reaction exhibited by tiny fireflies, as they light up the night in their efforts to find a mate. Bioluminescence is found throughout the animal kingdom and beyond, and the most extensive array of glow-in-the-dark creatures can be found in the ocean. Yet, interestingly, freshwater habitats have almost no bioluminescent organisms. Although modern science has allowed us to explore the inner workings of how this incredible biology occurs, bioluminescence has been fascinating humans for thousands of years. References to natural creatures glowing in the dark appear in the…

AMAZING GLOW-IN-THE-DARK ANIMALS

The diversity of dogs

Wolves and wild dogs Our four-legged friends evolved from wolves as a result of domestication and selective breeding. Although domestic dogs still show traits of their ancestry, such as marking territory and burying belongings, they are now a different species to their wild relatives. Terriers These dogs are often (but not always) small, wirehaired and feisty, and were originally bred as vermincatchers in the 19th century. The word terrier comes from the Latin word ‘terre’, meaning ‘earth’, and refers to their tendency to dive into burrows, barking furiously to flush out rodents, foxes, badgers and more. Northern Northern dog breeds hail from bitterly cold countries. The likes of Siberian huskies, Alaskan malamutes and Norwegian elkhounds are muscular breeds with thick fur. They were bred for hunting, herding and snow-sled pulling as well as for companionship…

The diversity of dogs

Life cycle of a frog

The cycle begins when frogs mate. The male holds the female in a position known as amplexus and fertilises her eggs as they are laid. A female frog can lay a clutch of around 3,000 to 6,000 eggs. Within each jelly-like sphere is a black dot – the developing tadpole. The embryos feed off the surrounding jelly as they grow, and then once they have developed rudimentary gills and a tail after about a week or a month (depending on the species), tadpoles hatch. The hatchlings feed on the rest of the frogspawn jelly mass, as well as any algae that has grown on it. Throughout the next few weeks the tadpoles undergo a fast metamorphosis. First their external gills disappear, replaced by internal gills, which in turn are replaced as lungs…

Life cycle of a frog

Anatomy of a sea anemone

Found in oceans all across the world, sea anemones belong to the group that also contains jellyfish and coral known as cnidaria. Resembling bright flowers underwater, anemones anchor themselves to rocks on the seabed. Although they have a nervous system, anemones don’t have brains. They have short, cylindrical, radially symmetrical bodies that use hydrostatic pressure to keep their structure. A circle of waving tentacles surrounds the anemone’s central mouth and these tentacles contain nematocysts – microscopic stinging structures that use neurotoxins to immobilise prey ready for eating. The stinging tentacles are dangerous to most marine creatures, but anemones are also known to strike up mutually beneficial relationships (known as symbiosis) with clownfish. The clownfish live in the anemones’ tentacles (they are immune to the sting) where they are protected and in return,…

Anatomy of a sea anemone

THE WORLD’S SMARTEST ANIMALS

Although humans don’t top the food chain, what we lack in physical ability we certainly make up for in mind. But that’s not to say we’re the only smart animals on the planet. Apes have long been considered our closest living relatives since we share over 90 per cent of their DNA, but we’re also surprisingly similar in the intellectual stakes to other species too. However, judging animal intelligence is not as easy as getting them to sit a multiple-choice exam. In fact, scientists have spent decades devising methods in order to weed out the brainless from the brainy. Researchers will spend years in the wild observing a species’ natural behaviour in order to get a better insight into how they learn, solve problems and make decisions. Combining that with controlled…

THE WORLD’S SMARTEST ANIMALS

Chiselling Woodpeckers use their beaks to bore into tree bark to obtain sap and insects. Their beaks have a springy structure that absorbs the impact of hitting a tree trunk 100 times a minute. Pursuit fishing This relatively flat bill helps aquatic birds to catch fish when they dive underwater. A cormorant is good at using its beak this way, piercing fish with the hooked upper bill. Dip netting Pelicans use their large, pouch-like bill to strain excess water once they have caught a mouthful of fish. It also attracts potential mates and scares away predators. Filter feeding Flamingos feed upside down using their upper bill as a scoop. Their fleshy tongues act like a pump to filter water, leaving behind the tiny marine life that these birds feed on. Fruit eating Toucans have an oversized beak for reaching…

Winter in the wild can be extreme. Low temperatures and a scarce amount of food make it difficult for many animals to survive. Some will migrate south during the winter months, but certain species of mammals, rodents and reptiles simply bed down and hibernate until spring instead. Hibernation is an extremely effective survival strategy that suspends the animal’s body functions and metabolism so it can preserve vital energy. This state of suspended animation will allow its body temperature to drop and its breathing and heart rate to slow down significantly. A chipmunk’s heart rate can drop from over 200 to just five beats per minute during hibernation, and fat-tailed dwarf lemurs will only take a breath once every 20 minutes! Hibernation is triggered by seasonal changes within the animal’s habitat. Hibernating species…

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