Historical iceberg scours imprinted on the West Greenland seafloor Published 19.06.2025

Figure 1. 3D seafloor image of Disko Bay showing iceberg scours on a shallow ground (less than 300 m deep). Insert photo was captured using an underwater video sled deployed from R/V Sanna.
Figure 2. West Greenland region showing reconstructed extents of the Greenland Ice Sheet at three different time intervals. Historical iceberg drift paths and ocean current directions are inferred from seafloor scour patterns.

 

Modern icebergs off the West Greenland coast typically scour depths of up to 300 meters, particularly in shallow areas, such as Disko and Melville Banks (Figure 1). However, our research also reveals large iceberg scours at much greater depths – down to 950 meters – along both the coastal and offshore regions of the West Greenland shelf. Since modern icebergs are not large enough to reach these depths, we know that these deep-water scours were formed by ancient icebergs, likely more than 10.000 years ago, when the Greenland Ice Sheet was much thicker and much more expansive, and the sea-level much lower.

By analyzing the size and orientation of these ancient scours, we can reconstruct past iceberg drift path, revealing how ocean currents once carried them. Figure 2 shows that scours oriented west-east reflect the direction of meltwater outflow and iceberg drift along the retreating ice sheet margin. In contrast, north-south scours suggest a sustained push from ocean currents – carrying warm water from the tropics via the Gulf Stream – that drove icebergs as far north as Melville Bay (Figure 2).

These findings indicate that a strong ocean current system was already active in the region around 13000 years ago. Unlike today, when currents primarily flow through the deep Baffin Basin and offshore troughs, this ancient circulation extended across the entire western Greenland coast, including shallow banks. Such extensive ocean activity may have accelerated the melting of the Greenland Ice Sheet after the last Ice Age. Thanks to the imprints left behind by icebergs scours on the seafloor, we are now gaining valuable insights into how ancient ocean currents shaped Greenland’s glacial history!

Icebergs in Greenland are massive chunks of ice that break off the Greenland Ice Sheet and drift through the ocean, with the majority of their mass submerged beneath the surface. The largest icebergs can reach the seafloor, scraping or ‘scouring’ it as they drift, driven by ocean circulation. These scours leave behind elongated channels flanked by sediment ridges, clearly visible in seafloor data collected by multibeam sonar and underwater videos