Geology magazine 1

The 驶Quick始 Earth Science Magazine

In this issue:

- How rocks can show us past climates.

- Have you ever heard of a limnic eruption?

- Antarctica has not always been like it is today.

# Geology is an all encompassing science that has aspects of physics, chemistry and biology within it. It both describes and explains the Earth始s history and current Earth processes. It can also be used to find natural resources, to help mitigate and predict natural hazards and to help map the ocean floor. In fact, geological sciences can be indirectly seen in many everyday items and activities. Plastics often require oil to be produced - this hydrocarbon is unearthed by geologists. Earthquake recording needs seismometers which are calibrated and developed by geologists. Water levels and water distribution are monitored by hydrologists, some of whom work in the field of geology. # Indeed geology is fundamental to our existence and allows us to work 驶in harmony始 with the planet on which we live. It unlocks the secrets of volcanoes, of the oceans, of the polar regions and even of the centre of our planet. It also allows us to delve into our past, and we can see what the Earth was like all those hundreds of millions of years ago. It is not limited to just our world, and geology can be used to examine other planets and moons. It is broad in nature, but specialised in knowledge - examining details from whole Earth systems to the rocks in one area. It is quite unlike any other subject and, with the dwindling reserves of petroleum that can be seen today, it is becoming more and more relevant in our modern world.

This short magazine has been written to celebrate the 2014 Earth Science Week and to try and encourage more school and college students to take up the subject at a higher level. This has been compiled in less than a week and if you have any queries with the magazine please email paverkonline@gmail.com. All contributors to any editions of the magazine are greatly thanked for their time.

Contents 1. Killer Lakes 2. The Thermometer in the chalk 3. What jobs can you do with a degree in Earth Sciences?

4. Did you know... ! ! ! ...that Antarctica was once teeming with life?

5. University Application tip 6. Common words in Earth Sciences

Killer Lakes The lakes that can kill people over 15 miles away ! ! ! ! ! ! ! ! ! !

August 15th,1984 Early in the morning Lake Monoun, West Province, Cameroon experienced a violent explosion. A cloud of gas piled into the air, water hit the surrounding land and 37 people were killed. Was this a terrorist attack? Was it caused by a volcano? Or was it something more sinister?

August 21st, 1986 Those that lived around the picturesque Lake Nyos in the Northwest Region of Cameroon were going about there everyday lives when they heard a loud sound followed by the sight of a cloud of gas reaching 100 metres into the air. This was channeled into a nearby valley and subsequently it suffocated around 1,700 people and killed countless other animals.

After two days the deadly cloud had gone while the lake had become shallower and full of floating dead organic matter. The large death toll of the event prompted an international effort to research what had caused this phenomenon.

What had caused these events?

These occurings were not an act of God or even directly linked to volcanoes. They were a rare type of natural disaster known as a limnic eruption, or a lake overturn. In this dissloved gas, mainly carbon dioxide, is ejected from a saturated lake. This gas is usually concentrated in the deepest parts where the higher pressure and lower temperatures means that more of it can be dissolved. Once this occurs the lake becomes very volatile and a small trigger could be all that is needed to set off an eruption. Triggers can take the form of landslides, earthquakes or even storms and these help to force the densely concentrated water up towards the surface. Here the pressure is lower and the temperature is higher so the carbon dioxide comes out of solution and starts to

form bubbles of gas. More and more water is then brought up in a 驶column始. The gas in the water is then ejected from the lake as a large plume and often Tsunamis follow as the water is displaced by the carbon dioxide.

There are two main theories for why the gas enters the river. Some say that carbon dioxide enters the water directly from volcanoes where as others put forth the argument that the carbon dioxide is released from decaying organic matter contained within the lake. Both these theories are feasible and show that an eruption could technically occur in many areas of the world, not just in volcanically active regions.# Consequences of an eruption The carbon dioxide emitted sinks to the ground as it is less dense than air, which is in turn forced upwards. Organisms requiring oxygen to breathe, like humans, thus suffocate and in many cases die. Due to the high concentrations of carbon dioxide acidification of body fluids and poisoning can also occur, increasing death tolls even further. The low temperature of the gas from the lake could cause frostbite, with evidence for this coming from the Lake Monoun eruption where certain blisters were found on the bodies of the dead, but this is only a theory that needs to be further explored. If enough gas was released a Tsunami could also entail, killing plants as well as animals. For instance in the Lake Nyos eruption vegetation was badly affected by the 5 metre wave that followed after the ejection of gas.

The Future Clearly a Limnic eruption is a very deadly natural disaster that should be take seriously. This is why there has been a worldwide effort to try and remove the gas in lakes that could experience this problem, currently only three worldwide.

For example pipes have been positioned in Lake Nyos and Lake Monoun to draw

the water saturated with carbon dioxide to the surface so that the carbon dioxide contained in it can be released. Much attention has also been focused on feasible methods of extracting the gas from Lake Kivu, the third possible site for an explosion. Due to its size, Lake Kivu is 2000 times large than Lake Nyos and has over two million people residing next to it, this has the potential to be very expensive.

If nothing is done then there could be wide scale death and destruction of vegetation.

Thankfully saturation levels are not quite high enough yet and hopefully a viable solution to the problem will be found in the not so distant future.

The Thermometer in the Chalk Understanding past climate change is critical in helping us predict how the environment will respond to human activities and change in the future. The instrumental climate record only dates back to a few centuries ago, so how else can we track ancient temperature variations?

Fortunately for the geologist, the earth leaves a vast spectrum of clues in the geological record, called climate ʻproxiesʼ.

These proxies can be as diverse as fossilised leaves and growth patterns in cave formations, but one of the most useful indicators for past temperature changes lies deep beneath the ocean surface in the form of calcium carbonate sediments.

The chemical properties of atoms are defined by their number of protons and each element has a specific proton number. However, elements can have a variable number of neutrons which only affect the atomʼs mass. The atomic mass

does not affect the atomʼs chemical properties but it does have an important impact on their physical properties. 99.9% of Hydrogen has a relative atomic mass of 1, and 99.8% of Oxygen has a mass of 16.

However, a very small number of Hydrogen atoms have a mass of 2, and a similarly small number of Oxygen atoms have a mass of 18. Therefore, whilst most water molecules - with the chemical formula H2O - have a mass of 18, a small number have higher masses, up to 22.

This is important because the heavier a molecule is, the slower it moves and the more energy is needed to raise it to a higher physical state. If you have a body of water and slowly heat it, the lighter water molecules are more likely to evaporate first. Therefore, the water vapour formed will be isotopically light and the remaining water will be isotopically heavy. This exact same process happens on the earth. As water evaporates from the oceans, mainly in the tropics, the water vapour formed is ʻlightʼ. There are some heavy water molecules but overall, it is lighter than the bulk composition of the ocean.

As the water vapour moves towards the polar regions along the temperature gradient, some water vapour precipitates as rain, which eventually travels back to the oceans, either directly or through rivers. The light water mixes with the heavy water in the ocean, maintaining the equilibrium. Just as lighter water molecules are more likely to evaporate, heavier water molecules are more likely to condense.

Therefore, as the air mass travels towards the poles, the vapour becomes even more enriched in light molecules.

As the air reaches the poles, water starts to precipitate as snow and if the surface is cold enough, the snow will remain and eventually form ice, forming ice sheets.

Unlike liquid water, ice is ʻlockedʼ in place and does not quickly return to the oceans.

Whilst the light water in rain is returned to the ocean to maintain the isotope equilibrium, the light water in ice is not

returned. As a result, the more water is stored as ice, the heavier oceanic water becomes.

The final step involves shell-forming marine organisms, that use calcium from dissolved rocks in combination with carbon from the atmosphere and oxygen from the oceans to form shells of calcium carbonate (CaCO3). When oxygen becomes part of calcium carbonate, it is ʻlocked upʼ and cannot return to the ocean. Eventually, these organisms die but these shells are generally not soluble so fall to the ocean floor and are preserved. The oxygen molecules in these calcium carbonate deposits are representative of the oxygen in the oceans so tracking how the amount of ʻheavyʼ oxygen changes in these deposits tells us how the amount of ice on the planet and therefore temperature changed over time. Geologists extract cores from the sediment and use techniques such as mass spectroscopy to analyse how the isotope ratios change over time. In effect, the sediments are massive global thermometers. When more ice is formed and the temperature drops, the amount of ʻheavyʼ oxygen in the sediment increases as more ʻlightʼ oxygen is stored in the ice sheets. When ice melts and the temperature rises, the amount of heavy oxygen in the sediment decreases as the light oxygen in the ice sheets is released.

For the last 2.5 million years, the planet has been oscillating between periods where ice sheets have expanded significantly beyond the poles, called glacial periods or ʻice-agesʼ, and periods where ice sheets have been confined to the poles, called interglacial periods.

Analysing the oxygen isotope record in these calcium carbonate records has allowed us to discover and understand these oscillations and cross referencing these with other proxies that give us other useful pieces of information such as atmospheric carbon dioxide concentrations or wind intensity allows us to understand the dynamics of our climate and help us

make predictions about how the climate will change in the near and far future.

What jobs can you do with a degree in Earth Sciences? # When people think of geology they mainly think of rocks. For this reason, many believe that the only real jobs associated with the degree are to do with academia - indeed, there are jobs in this area, but there are also many more in others. # Take the petroleum industry. Many companies involved in this hire geologists and geophysicists to model flows, find new resources and map ocean beds and the rocks beneath them. Indeed earth scientists are highly sought after by these corporations and for that reason geologists often get paid well. Working days can involve both desk work in offices and visiting exploration sites, such as oil rigs.

Due to these reasons many graduates go to work in this industry. Many also find careers in the mining industries, in which geologists are needed to find mineral deposits and help with the construction of mines. Working for either mining or petroleum companies can be a truly ʻinternationalʼ experience and can involve a lot of traveling to other countries, where the largest majority of mineral and petroleum deposits are located. # As said at the beginning many also go onto jobs in academia. This involves research and often teaching, but it is much more interesting than most perceive it to be. All involved in this area get to travel to areas relevant to their research, including but not limited to: Antarctica, Greenland and even the vast oceans. They look at things from the extent of ice caps to the fossils in areas local to them and they can work at institutions across the world: from Australia to the United States. Salaries are

also high at most universities and job security has the potential to be very good. # Some also enter engineering rolls, after further training. The most high demand position is probably that of a petroleum engineer; a challenging job which requires engineers to get the greatest recovery of hydrocarbons at the lowest costs and with the least number of environmental impacts. This is certainly a well paid job and petroleum engineers work closely with geoscientists, showing how linked the two positions are. Away from engineering, lots of earth scientists also go and work in environmental conservation, where they can use, to their advantage, skills they learned during their geoscience degrees, such as: appreciation of landscapes, how the natural world evolves and knowledge of how to work in the outdoors. # Lastly, a significant minority of earth science graduates go and work in completely unrelated degrees. The skills of data analysis and the ability to understand and work out difficult problems has meant that geologists are very employable. These 驶other始 fields of work include accountancy, banking and teaching. # Hopefully this shows that a degree in Earth Sciences opens up a whole variety of well paying careers which are very interesting and continuously changing.

Did you know... ...that Antarctica was once teeming with life?

Antarctica is the coldest, windiest and driest continent on Earth. Few lifeforms can live here due to these extreme conditions. Yet, the continent has not always been this way and it used to support much more life than it does today.

During the paleozoic era of 540-250 Ma (million years ago) the continent was part of the supercontinent, Gondwana - a precursor to the famous Pangaea. At this time Antarctica was actually located much

closer to the equator than it is at the present, and thus the continent had a climate warm enough to support life. Via fossils found in rocks and due to radar, scientists have been able to show that the area had a climate suitable to supporting plants and animals. Large plains drained by rivers have been indicated to have existed under the extremely thick ice that now covers the continent. The presence of flatter topography indicates limited erosion and possibly a warmer climate where ice could not erode the area into large valleys and mountain ranges. Furthermore, the discovery of the fossils of organisms and the remains of spores in Antarctica has given greater evidence to the fact that Antarctica once supported life. So, next time you see Antarctica on the news, just remember that it too used to be like the rest of the world.

Did you know? An article Less than 250 words on a single topic.

University Application tip Doing research on a niche topic and then writing an article about it can show that you have a passion for certain areas in the geological sciences.

Examples for areas of research: - The geology of your local area - Famous geological hazards (like volcanoes)

- The geological history of an area It may also be a good idea to take any articles you have written with you to any interviews you may have, just incase the interviewers want to see them.

Common words in Earth Sciences Sedimentary rock: These rocks are formed when sediments which have settled on ocean/sea floors over millions of years have been compressed into rock.

Igneous rock: Those rocks are formed when molten material solidifies.

Metamorphic rock: These rocks are formed when existing sedimentary or igneous rocks are changed due to intense heat and pressure.

Supercontinent: A large block of land formed when separate land masses collide and join together.

Plate tectonics: A theory that indicates that the earth始s crust is separated into numerous 驶plates始 which move around on top of the mantle below.

To write an article for a future edition please email paverkonline@gmail.com.