By the excavation for a new subway station at Trianglen in Østerbro in Copenhagen, scientists have discovered something more extraordinary than just stone, gravel and sand.
In connection with the excavation is the tracks for a completely new and previously unknown interglacial period in Denmark emerged. It writes Science.dk, and found is published in the journal Boreas.
By analyzing, among other amino acids, protein building blocks, the researchers could demonstrate that the newly discovered interglacial period took place about 200,000 years ago.
An interglacial period is a warm period like the one we live in now, between the two glaciations. The new discovery covers the total of the fifth interglacial period, we now know from the Denmark, in addition to the one we live in now.
Geologist Ole Bennike, who is senior researcher at The Geological survey of Denmark and Greenland (GEUS), find it incredible that found is done in Copenhagen.
- It was definitely a surprise, because there are made lots of holes in Copenhagen. It is highly unusual to encounter such mellemistidsaflejringer, he says to Ritzau.
over the past millions of years, the climate alternated between glacial and interglacial periods. The current interglacial period started about 11.700 years ago, where the difference between summer and winter was at its highest.
But although scientists know that the climate globally has fluctuated much, they have in Denmark, so far only found direct traces of the four interglacial periods. The fourth was found in 2013.
Ole Bennike think definitely, in the future will find clues from several interglacial periods.
- Our ability to date the layers become better and better. There will be developed new methods for dating some of those old layers, he says.
Within the past decade has iskerneboringer from Antarctica also given clear indications that there have been great fluctuations in the climate through time, tells seniorforskeren.
In Denmark we do not have the interconnecting layers of the earth or the seabed, which can tell geologists exactly how the climate has evolved.
It is due to landscape time and time again has been "planed down" of isfremstød through time.
It explains the emeritus professor Bent Vad Odgaard, and as a researcher in climate change and ecosystems in the geological scale at the Department of Geoscience at Aarhus University, to Science.dk.
It means that the strata has been eroded – it will say that they are either located helter-skelter or simply is broken, and that today only fragments of the past.
- So even if it's not every day we find deposits from the new interglacial periods, on the other hand not at all surprising, when we do, say, Bent Vad Odgaard, who took the fourth interglacial period, Science.dk.