The observation by Heinrich (1988) that, during the last glacial period, much of the input of ice‐rafted detritus to the North Atlantic sediments may have occurred as a succession of catastrophic events, rekindled interest on the history of the northern ice sheets over the last glacial period. In this paper, we present a rapid method to study the distribution of these events (both in space and time) using whole core low‐field magnetic susceptibility. We report on approximately 20 cores covering the last 150 to 250 kyr. Well‐defined patterns of ice‐rafted detritus appear during periods of large continental ice‐sheet extent, although these are not always associated within their maxima. Most of the events may be traced across the North Atlantic Ocean. For the six most recent Heinrich layers (HL), two distinct patterns exist: HL1, HL2, HL4, HL5 are distributed along the northern boundary of the Glacial Polar Front, over most of the North Atlantic between ≈40° and 50°N; HL3 is more restricted to the central and eastern part of the northern Atlantic. The Nd‐Sr isotopic composition of the material constituting different Heinrich events indicates the different provenance of the two patterns: HL3 has a typical Scandinavia‐Arctic‐Icelandic “young crust” signature, and the others have a large component of northern Quebec and northern West Greenland “old crust” material. These isotopic results, obtained on core SU‐9008 from the North American basin, are in agreement with the study by Jantschik and Huon (1992), who used K‐Ar dating of silt‐ and clay‐size fractions of an eastern basin core (ME‐68‐89). These data confirm the large spatial scale of these events, and the enormous amount of ice‐rafted detritus they represent.

Sr and Nd isotopic compositions have been measured on the lithic fraction of last climatic cycle sediments from the North Atlantic (≈40°N/≈60°N), in order to identify the origins of the particles. From the reconstruction of their transport pathways, we deduce the mechanisms that explain their distributions. The main source regions are the Canadian shield (mostly the area of Baffin Bay and western Greenland), the Scandinavian shield, the European region (British Isles and Bay of Biscay), and Iceland. We observe a significant glacial/interglacial contrast, characterized by a dominant Icelandic input via near‐bottom transport by North Atlantic Deep Water (NADW) during the interglacials and a largely continent‐derived contribution of surface‐transported, ice‐rafted detritus (IRD) during the glacial period. During the last glacial period, the Heinrich events (abrupt, massive discharges of IRD) originated not only from the Laurentide ice sheet as heretofore envisioned but also from other sources. Three other major North Atlantic ice sheets (Fennoscandian, British Isles, and Icelandic) probably surged simultaneously, discharging ice and IRD into the North Atlantic. As opposed to theories implying a unique, Laurentide origin [Gwiazda et al., 1995] driven by an internal mechanism [McAyeal, 1993], we confirm that the Icelandic and the Fennoscandian ice sheets also surged as recently proposed by other authors, and we here also distinguish a possible detrital contribution from the British Isles ice sheet. This pan‐North Atlantic phenomenon thus requires a common regional, external forcing.

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