A group of international researchers, including a glaciologist from Newcastle University in the UK, has uncovered exceptionally well-preserved glacial structures lying nearly 1 kilometer beneath the North Sea.
The research team employed seismic sound wave data to uncover Ice Age formations hidden below significant layers of mud in the North Sea. Their findings, published in the journal Science Advances, indicate that these formations were created around 1 million years ago, when an ice sheet centered over Norway reached toward the British Isles.
This discovery is significant as it aligns with a period of global cooling known as the Mid-Pleistocene Transition.
Understanding glacial landforms offers insights into how historic ice sheets reacted to climate changes, aiding in more accurate predictions regarding contemporary ice sheets’ responses to global warming. However, identifying these formations can be challenging due to thick sediment layers covering them.
Dr. Christine Batchelor, a Senior Lecturer in Physical Geography at Newcastle University, significantly contributed to the mapping and interpretation of these landforms. “To grasp the connections between ice sheets and climate, we must explore how past ice sheets reacted to long-term climatic shifts,” Dr. Batchelor stated. “Our findings, drawn from modern seismic data, indicate a considerable expansion of ice sheets in northwest Europe in response to climate cooling about 1 million years ago.”
Dr. Dag Ottesen from the Geological Survey of Norway, who led the paper, remarked: “The availability of 3D seismic data from the North Sea made this study possible, allowing us to analyze the buried landforms in remarkable detail.”
The 3D seismic technology was initially developed to evaluate sediment suitability for oil and gas or renewable energy projects. However, it also proves valuable for investigating glacially formed buried landforms.
The detailed mapping reveals streamlined features shaped under the former ice sheet and ridges that reflect the ice sheet’s retreat. Despite their age, these landforms closely resemble features created by more recent ice sheets.
The hidden formations enhance our understanding of how ice sheets withdraw. For these subtle landforms to remain unaltered, the previous ice sheet would have needed to retreat swiftly through lift-off and flotation of its leading edge.
In addition to glacial formations, the researchers discovered long furrows etched into the old seabed, believed to have been formed by powerful ocean currents. These features are buried even deeper than the glacial formations, indicating they were formed before the ice sheet’s advance.
“Our high-resolution data show that the shape and dimensions of the furrows align with those created by ocean currents,” Dr. Ottesen explained. “This changes previous interpretations of these features as glacial formations, altering our understanding of North Sea glacial history.”
This research offers new insights into the evolution of the North Sea during the recent geological past. It reveals that before about 1 million years ago, the North Sea was characterized by strong ocean currents, after which it became predominantly affected by ice sheets.
The research team recognizes a limitation in their study regarding the lack of data on the exact age of the landforms.
“There is now an abundance of seismic data available for the North Sea,” said Dr. Batchelor. “The next step is to gather long sediment cores to help researchers better determine the timing of glacial events.”
Other co-authors include Helge Løseth from Equinor ASA in Trondheim and Harald Brunstad from Aker BP ASA, also in Trondheim.
