Excavations for Copenhagen Metro dig up evidence of interglacial period

An unexpected discovery was made as a result of excavation work at the construction site of a new underground rail station at Trianglen in Copenhagen.

Excavations for Copenhagen Metro dig up evidence of interglacial period
A 2016 photo showing construction work on the Copenhagen Metro. Photo: Thomas Lekfeldt/Ritzau Scanpix

Work on the new Metro station revealed traces of a hitherto unknown interglacial period in Denmark, science media writes based on research published in the journal Boreas.

Analysis of amino acids enabled researchers to demonstrate the existence of a period around 200,000 years ago which punctuated two ice ages, otherwise known as an interglacial.

An interglacial is a warmer period such as the one we are currently living in, which falls between two ice ages.

The Copenhagen Metro find is remarkable due to its location, according to Ole Bennike, a geologist with the Geological Survey of Denmark and Greenland (GEUS).

“This is certainly a surprise, because lots of drillings have been done in Copenhagen. It’s very unlikely to come across these types of interglacial deposits,” Bennike told Ritzau.

Global climate has varied between ice ages and interglacials for millions of years. The current interglacial began around 11,700 years ago.

Researchers have previously found evidence of four interglacial periods in Denmark, with the new find representing the fifth.

Further discoveries in future are likely, according to Bennike.

“Our ability to date [sediment] layers is becoming better and better. New methods are being developed with which to date these layers,” he said.

READ ALSO: Crater bigger than Paris is discovered under Greenland ice


How a Viking king inspired one of our best-known modern technologies

A Swede and American tell the story of how they hatched the idea for the moniker 'Bluetooth' over beers.

A Danish 16th-century paining of Viking king Harald Bluetooth
A Danish 16th-century paining of Viking king Harald Bluetooth. Photo: Wikimedia Commons/Public domain

At the end of the 1990s, Sven Mattisson, a Swedish engineer working at telecom group Ericsson, and Jim Kardach, an American employed by Intel, were among those developing the revolutionary technology.

In 1998, at the dawn of the “wireless” era, the two men were part of an international consortium that created a universal standard for the technology first developed by Ericsson in 1994.

But prior to that, they had struggled to pitch their wireless products. Intel had its Biz-RF wireless programme, Ericsson had MC-Link, while Nokia had its Low Power RF. Kardach, Mattisson and others presented their ideas at a seminar in Toronto in late 1997.

“Jim and I said that people did not appreciate what we presented,” Mattisson, now 65 and winding down his career at Ericsson, recalled in a recent interview with AFP.

The engineer, who had travelled all the way to Canada from Sweden for the one-hour pitch, decided to hang out with Kardach for the evening before flying home.

“We received a lukewarm reception of our confusing proposal, and it was at this time I realised we needed a codename for the project which everyone could use,” Kardach explained in a long account on his webpage.

‘Chauvinistic story’

To drown their sorrows, the two men headed for a local Toronto bar and ended up talking about history, one of Kardach’s passions. “We had some beers… and Jim is interested in history so he asked me about Vikings, so we talked at length about that,” said Mattisson, admitting that his recollection of that historic night is now somewhat foggy.

Kardach said all he knew about Vikings was that they ran “around with horned helmets raiding and looting places, and that they were crazy chiefs.”

Mattisson recommended Kardach read a well-known Swedish historical novel about the Vikings, entitled “The Long Ships”.

Set in the 10th century – “a chauvinistic story” about a boy taken hostage by Vikings, says Mattisson – one name in the book caught Kardach’s attention: that of the king of Denmark, Harald “Bluetooth” Gormsson.

A Bluetooth adapter from 2004. Photo: Stefan Gustavsson/SvD/TT


An important historic figure in Scandinavia in the 10th century, the king of Denmark’s nickname is said to refer to a dead tooth, or, as other tales have it, to his liking for blueberries or even a simple translation error.

During his reign, Denmark turned its back on its pagan beliefs and Norse gods, gradually converting to Christianity.

But he is best known for having united Norway and Denmark in a union that lasted until 1814.

A king who unified Scandinavian rivals – the parallel delighted those seeking to unite the PC and cellular industries with a short-range wireless link.

And the reference to the king goes beyond the name: the Bluetooth logo, which at first glance resembles a geometric squiggle, is in fact a superimposition of the runes for the letters “H” and “B”, the king’s initials.

Low-cost and with low power consumption, Bluetooth was finally launched in May 1998, using technology allowing computer devices to communicate with each other in short range without fixed cables.

The first consumer device equipped with the technology hit the market in 1999, and its name, which was initially meant to be temporary until something better was devised, became permanent.