Scientists have divided the ocean into five main layers. These layers, known as “zones”, extend from the surface to the most extreme depths where light can no longer penetrate. These deep zones are where some of the most bizarre and fascinating creatures can be found. As we dive deeper into these largely unexplored places, the temperature drops and the pressure increases at an astounding rate. The following chart lists each of these zones in order of depth.

Epipelagic Zone - The first of these layers is known as the Epipelagic Zone and extends from the surface to 200 meters (656 feet). It is in this zone that most of the visible light exists.

Mesopelagic Zone - Next is the Mesopelagic Zone, extending from 200 meters (656 feet) to 1000 meters (3281 feet). The mesopelagic zone is sometimes referred to as the twilight zone or the midwater zone. The light that penetrates to this depth is extremely faint. It is in this zone that we begin to see the twinkling lights of bioluminescent creatures. A great diversity of strange and bizarre fishes can be found here.

Bathypelagic Zone - The next layer is called the Bathypelaic Zone. It extends from 1000 meters (3281 feet) down to 4000 meters (13,124 feet). Here the only visible light is that produced by the creatures themselves. The water pressure at this depth is immense, but a surprisingly large number of creatures can be found here. Sperm whales can dive down to this level in search of food. Most of the animals that live at these depths are black or red in color due to the lack of light.

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Above is a clickable image showing the layout of earth’s tectonic plates, as scientists have them outlined today. Plate margins are the edges of the plates, where all the awesome power of nature is released in earthquakes and volcanoes! To go back to the page you were just reading, click on that part of the map. To find out more about each of the three types of plate boundaries, click on them!

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The environmental impact of India’s Nano car

It may be the world’s cheapest car, but is this the direction that India’s promising engineering industry should be taking?

Tata Motors this week launched the Tata Nano, a compact, shoe-boxy sort of car, with four tiny wheels and one wing mirror.

Environmentalists are already crying murder, saying that this will just encourage more pollution and congestion in a nation that is already suffering severely from both. So I thought I would have a quick look at how things stack up.

The Tata Nano will meet European emissions standards on exhaust. If you want to see details, check out the Euro IV line in this table. Bear in mind that exhaust emissions standards regulate the particles that make up smog, not emissions of the greenhouse gas carbon dioxide (which the EU does not currently regulate, although it’s trying).

The numbers come out in favour of the Tata Nano. Euro IV standards are more stringent than those in place for the motorcycles and scooters, which make up a big chunk of India’s motorised traffic.

For instance, according to the Indian Federation of Automobile Dealers Association and the Society for Indian Automobile Manufacturers, the 2005 standards for two-wheelers limited carbon monoxide, hydrocarbon, and NOx emissions to 1.5 g/km travelled – compare that to just 0.5 g/km (carbon monoxide) and 0.3 g/km (hydrocarbon and NOx) under Euro IV.

But look at fuel efficiency and the balance is flipped. Tata’s Nano travels 21 km for every litre of fuel it is fed, compared to up to 80 km/l you could achieve with a two-wheeler. That means not only a larger bill for the owner, but also more CO₂ chucked into the atmosphere.

So, the Nano will bring less ground-level pollution but more greenhouse gases. Ideally, you would want to see less of both (which is for instance what the Vikram electric 3-wheeler, pictured left, offered).

Still, maybe this is the first of a new wave of ingenious new car models to be produced in India. Given the nation’s considerable engineering workforce, and the growing demand for green transportation, it could be lucrative for Indian companies to start shifting their attentions to supplying the world with new environmentally friendly forms of transportation.

Tata is a massive company, but so far its only environmental line of business is a joint venture in solar energy with BP. Time for a change?

Catherine Brahic, online environment reproter

Have humans created a new geological age?

What does it take to bring on a new geological age? According to members of the Stratigraphy Commission of the Geological Society of London, one way of going about it would be to:

1. Change the atmosphere’s composition, thus modifying plants
2. Change the distribution and diversity of species, thereby changing the future fossil record
3. Acidify the oceans, which will modify mineral deposits on the ocean floor

Sound familiar? Yes, you guessed it – maybe this is the new geological age.

The suggestion that the overtaking of planet Earth by one species – humans – kicked off a new age was first made by Paul Crutzen in 2002. Crutzen, a Nobel prize-winning chemist, said we should now consider that we are living in the Anthropocene, an age dominated by human activities.

Since then, his term has caught on. Stick it in Google and you get over 42,000 hits. It’s got its own Wikipedia entry. Scientists are using it – the International Geosphere-Biosphere Programme recently published a document with a chapter devoted to it. (Bill Gates hasn’t caught on though – my spellchecker doesn’t recognise it.)

In spite of all this, and the apparent logic behind it, declaring the advent of a new geological age is no small matter. So although we may all – and I include scientists in that “we” – be perfectly happy to talk about the evils and blessings of the Anthropocene, we will not officially be living in it until a group of scientists at the International Union of Geological Sciences puts their seal on the term.

And that won’t happen – if indeed it does – for several more years.

To kick-start the process of formalising the term, Jan Zalasiewicz and his colleagues at the Stratigraphy Commission of the Geological Society of London have laid down their case in favour. Their defence is featured on the cover of the February 2008 issue of GSA Today, published by the Geological Society of America.

To some, it may seem obvious that humans are massively changing the environment, but what Zalasiewicz had to do was show that 10, 100, 500 million years down the line, if you were to slice through a chunk of sediment you would be able to identify a distinct layer that corresponds to our reign on Earth.

The group says there is enough evidence around to suggest this will be the case. Ocean acidification, if it continues, could bring an end to corals which will change the nature of ocean rocks. Humans activities have triggered huge amounts of erosion, generating a new layer of sediment.

Widespread agriculture is replacing natural vegetation with large expanses of single crops. Cutting down forests, draining marshlands and peat bogs, transforming the prairies have pushed out the animal and plant species that live there and caused them to go extinct. All of the above will mean that one day, the fossil record of our time will look very different to the pre-Anthropocene record.

If indeed we are now in a new age, when did it begin? That’s a bit tricky, seeing as it is too early to study the physical slice of sediment and find the bottom of that distinctive new layer in a form that can be recognised around the world. (I’m picturing the geologists of the future pulling out sediment cores looking for the layer of plastic debris that marks the Anthropocene.)

So Zalasiewicz says the date should be set to 1800, because that’s when human population hit 1 billion and started to grow at an alarming rate and when a number of changes associated with industrialisation suddenly took off.

The team doesn’t go so far as saying that we are in a new era – although they caution that a mass extinction brought about by humans would be an argument in favour of that. Instead, they are just arguing for a new epoch (a sub-division of an era). So bye bye Holocene, but the Quaternary stays.

I’m tempted to wonder how anyone could object to formalising the Anthropocene. Most scientists agree that human activities are driving widespread environmental changes that reach down to the bottom of the seas, high up into the atmosphere, and from pole to pole. But there will no doubt be objections, the main one amongst them being, possibly, that it is simply too soon to say.

After all, stratigraphy experts normally spend their time defining epochs that are long gone. New epochs haven’t exactly been defined “live” before.

Besides, who knows – if the governments of the world get their acts together and we all start tightening those carbon purse strings, maybe, just maybe, we could manage to stay in the Holocene after all?

Catherine Brahic, online environment reporter

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