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ice-rafted debris
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Map of the North Atlantic Ocean showing the extent of the ice-rafted debris (IRD) belt shaded in purple, stretching from the eastern coast of North America toward Europe. The map also depicts the locations of Greenland, Iceland, the United Kingdom, and Ireland, areas covered by ice during glacial maxima in light gray, and the paths of ocean currents, with the Gulf Stream and other warm currents marked in red and cool currents in blue.
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ice-rafted debris

geology
Also known as: IRD
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Map of the North Atlantic Ocean showing the extent of the ice-rafted debris (IRD) belt shaded in purple, stretching from the eastern coast of North America toward Europe. The map also depicts the locations of Greenland, Iceland, the United Kingdom, and Ireland, areas covered by ice during glacial maxima in light gray, and the paths of ocean currents, with the Gulf Stream and other warm currents marked in red and cool currents in blue.
ice-rafted debris belt Icebergs released into the North Atlantic during the initial warming intervals that follow cool periods have carried coarse-grained rocky debris into the North Atlantic Ocean to latitudes between 40° N and 55° N. This material falls away as the icebergs melt, creating a large ice-rafted debris (IRD) belt on the ocean floor.

Ice-rafted debris (IRD) refers to rock fragments and sediment transported by ice, such as icebergs or sea ice, and deposited in marine environments. This debris differs from the local bedrock and can range in size from pebbles to large boulders.12

When icebergs run aground, they can create deep furrows on the seabed, known as iceberg scours, which can extend for many kilometers. Both Arctic and Antarctic icebergs carry sediment on their undersides and tops, which is deposited as the ice melts.1

The presence of IRD in sediment cores is a key indicator of past iceberg or sea ice activity. By mapping the locations and types of rock in IRD, geologists can reconstruct the distribution of ice and cold surface waters in the past, and even identify the source regions of the icebergs. This method has been used to study glacial periods and has also provided insights into the direction of glacial movement and the location of mineral deposits.12

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2 Britannica Sources
  1. iceberg - Iceberg scour and sediment transport
  2. erratic

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