Category Social Sciences

WHAT IS AN ESKER?

Sometimes a stream cuts a channel under a slow-moving glacier, creating a long, winding ridge of sand and gravel that is called an esker. Before the glacier melted, the banks of these streams were defined by glacier ice. The deposited gravel now stands high above the surrounding land.

An esker is an attractive landform formed through fluvioglacial deposition. It is a winding ridge of low-lying stratified sand or gravel dominating the terrain and providing the vintage point and dry routes. An esker occurs in a glaciated area or a formerly glaciated region, especially in Europe and North America. The esker lies on valley floor within the ice margins marked by a moraine system suggesting that the eskers are formed beneath the glacier. The word esker is an Irish word meaning a ridge or an elevation which separates two plains. The term is also used to refer to ridges which are deposits of fluvioglacial material. Eskers vary in size and shapes with most of them being sinuous. The longest eskers are continuous and measure few kilometers while most of them are short and discontinuous.

Eskers are formed on washed sands and gravel. Most eskers are formed within ice-walled tunnel by streams which flow under and within glaciers. When the ice wall melts away, water deposits remain as winding ridges. Eskers can also be formed above the glacier through the accumulation of sediments in supraglacial channels. Eskers are formed at the terminal zones of glaciers where the ice is flowing relatively slowly. The melt water collects and flows through a network of tunnels. This water carries highly charged with debris which is composed of coarse-grained gravel which are stratified and sorted. The shape and size of the subglacial tunnel are determined by the flow and melting of the ice. The form of the tunnel then determines the shape and structure of an esker.

Credit: World Atlas

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HOW DO WE KNOW THAT ICE ONCE COVERED AN AREA?

A study of rocks found in an area reveals much about its past. The debris and way that sediments have been changed and distorted gives evidence of ice covering that area. Also, land eroded by ice shows certain typical landforms such as glaciated valleys with cirques, arêtes and horns. All these indicate the presence of ice sometime in the past.

Sea ice may have covered the Earth’s surface all the way to the equator hundreds of millions of years ago, a new study finds, adding more evidence to the theory that a “snowball Earth” once existed.

The finding, detailed in the March 5 issue of the journal Science, also has implications for the survival and evolution of life on Earth through this bitter ice age.

Geologists found evidence that tropical areas were once covered by glaciers by examining ancient tropical rocks that are now found in remote northwestern Canada. These rocks have moved because the Earth’s surfaces, and the rocks on it, are in constant motion, pushed around by the roiling currents of the planet’s interior, a process called plate tectonics.

Credit: Live Science

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What is a spit?

A spit is a narrow, extended piece of land that develops where a coastline sharply turns in towards the landmass. Attached to the coast at one end, the spit seems to grow out of it, as the movement of waves and tides deposits sand and pebbles at the angle of the landmass. The other end extends out into the sea, growing longer over time as more debris accumulates along it.

Spit is a landform in geography that is created from the deposition of the sand by the tide movements. One end of the spit remains attached to the mainland while the other end is open out in the water. It is narrow and elongated. Also known as sandspit, this type of landform is found off the coasts or the lake shores.

Spits are usually formed when re-entrance takes place by the longshore drift process from longshore currents. When waves at an oblique angle meet the beach, drift occurs. There is a deposit of sediment in a narrow strip in zigzag pattern moving down the beach. The same waves also cause longshore currents that complement the formation of the spit.

At the re-entrance, the longshore current spreads out or dissipates and not being able to carry the full load, drops much of the sediment which is called deposition. The longshore or littoral drift continues to transport sediment with the help of this submerged bar of deposit into the open waters alongside the beach in the direction the waves are breaking

This process forms an above-water spit. The formation of spit will continue out into the sea until the water pressure obstructs in the deposition of sand. As it grows, it becomes stable and often fertile; vegetation starts to grow and supports habitation.

Credit: Earth Eclipse

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1000 trees are presently ‘walking’ down the streets of the Dutch city of Leeuwarden

1000 trees are presently walking down the streets of the city of Leeuwarden, Netherlands. Or rather, the indigenous trees planted in big wooden containers are being lugged around by volunteers. The idea is to let people experience a greener and cleaner alternative.

The unique initiative has been launched as part of the art project ‘Bosk, envisaged by architect Bruno Doedens and his collaborator, the late Joop Mulder.

The trees will keep moving around the city till August 14, after which they will be planted across the city. The idea emerged from Doedens 2021 essay Planet Paradise. The essay questions the relationship of humans with the natural world.

Bosk means forest in the local Frisian language. The move is an attempt to raise awareness about climate change. The trees are being moved by thousands of volunteers and roads are closed when the trees are walking. The trees rest on the weekend.

It all started in the month of May, when volunteers started moving the trees in huge wooden containers. After starting their journey, the trees first stopped at Stationsplein. outside Leeuwarden’s train station.

Whilst the trees aren’t moving, seating areas are provided between the trees to let the people experience life when there is more green cover. Around 60-70 varieties of native trees such as maple, oak, elm, willow, alder, and ash are planted in the wooden containers.

QR codes have been given which lets one know the details such as the species name, its lifespan, soil type, and so on. The city gardening team gets an alert whenever water is required by the tree. A soil sensor alert has been provided for this.

 The trees will get their permanent home in the city after 100 days. The trees will trundle down these roads until August 14 and will later be planted across the city where the greenery is limited.

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What is Deus Ex Machina?

Deus Ex Machina is Latin for “God from the machine”. The first literary mention of the phrase can be traced back to Aristotle’s book on Poetics where the philosopher critiques this practice as a weak plot device. Originating in the Greek theatre, this phrase describes a theatrical trend of the time where the protagonist who is stuck in an unresolvable situation is saved by the intervention of a god or deity who would suddenly appear on the stage by either parting the clouds in the sky with the assistance of a crane which would lower the divine being to a platform or rise from under the stage by means of a trap door, hence the name god from the machine.

The Greek playwright Euripides was a great proponent of this practice. However, criticising this spectacle, Aristotle argued that this irrational plot device startled the audience and manipulated their response to the play, diverting their attention away from the plot and the relationships between the characters.

In modern times… Although we have come a long way in our storytelling, sometimes writers still struggle to give their stories a logical and purposeful ending. In such cases a Deus Ex Machina refers to those moments in a narrative when an otherwise unsolvable situation is resolved by the intervention of a person, power, or an (accidental) event that doesn’t have any precedent in the story. Such accidents tend to be viewed with disdain by modern audience, and are perceived as a sign of lack of initiative and creativity on the part of the author or creator.

A classic example of this in fiction is the ending of William Golding’s Lord of the Flies which shows a  naval officer who happens to be passing the island saving the children and taking them back to civilisation. In movies, this device is exemplified by endings like that of Harry Potter and Chamber of Secrets where in the climax out of the blue, Faux the Phoenix flies down into the chamber and gives Harry the sorting hat with the Sword of Gryffindor allowing him to kill the monstrous Basilisk, and flies them out to safety when the chamber starts to disintegrate.

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The river as a dumpyard

The Mekong is one of the longest rivers in the world, cutting across several Asian regions from Tibet and China to Thailand and Cambodia. But spanning a large area means the threats it faces are just as huge. What are they? Come, let’s find out.

Waste generated in any region is disposed of in many ways, including being dumped at landfills. (Only a minuscule fragment of waste is recycled globally.) Some countries export their waste. Several Asian countries have been taking in plastic waste from such countries, without really being equipped to handle waste disposal safely. In addition, these Asian countries have their own waste to deal with. The waste in landfills reach rivers and oceans through winds, rains, and drains. One such river is the Mekong. Painfully, three “of the worst six plastic polluting countries China, – Thailand, and Vietnam – have a presence in Mekong”, meaning the quantum of waste this river takes in is huge and increasing. The pandemic, with its masks, plastic sanitiser containers, take-away plastic boxes, etc., has exacerbated the situation. And, this is of grave concern.

The Mekong is a treasure trove of biodiversity – several species of plants, birds, reptiles, and fishes call the river and its surrounding regions home. But in the current scenario, rubbish is finding its way into the water, endangering wildlife. Animals and birds are in danger of being affected by plastic debris through entanglement or ingestion. There have been instances of dead whales “turning up in Thailand and Indonesia with many kilograms of plastics in their stomachs”. It is not just wildlife that’s affected. When humans consume creatures such as fish, we end up consuming plastic, which has the potential to cause serious health problems such as cancer. Since rivers drain into larger waterbodies such as seas (the Mekong mixes with the South China Sea) and oceans, the pollution they carry is transferred too.

An increase in the pollution of waterbodies is an indication of increasing pollution on land. And a grim reminder that unless we change our lifestyles to make this planet greener, we are likely to face the negative consequences of our own actions.

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