Excavations for Copenhagen Metro dig up evidence of interglacial period

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

The soil layers at the Trianglen excavation, as seen in the picture here, lie in the same order as the layers
at the Copenhagen Free Harbour, which have long been a thorn in the eye of the geologists
[Credit: Joakim Stiel Korshøj from the company Geo]

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).

In the cliff at Trelde, Professor Emeritus Bent Vad Odgaard found in 2013 an unprecedented
intermediate period in Denmark [Credit: Bent Vad Odgaard]

“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.

Aerial view of the Copenhagen Metro construction site [Credit: Copenhagen Metro]

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.

Source: The Local [February 01, 2019]

TANN

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