Fig. 1.

Source areas of ice-rafted debris that drifted to ODP Site 913. Arctic Ocean source areas that contribute significant numbers of Fe oxide grains to any one sample at Site 913 (based on a chemical fingerprinting method⁴³) are circled. Red circles indicate more than nine grains; black circles indicate more than 2 grains. Each source area is numbered (note that colors are only for ease of distinguishing one area from an adjacent area). Data on provenance are in Supplementary Data 1–2. The drift tracks are based on modern surface circulation^44,51,52. The red dashed track is a possible pathway for a small amount of ice⁷⁰. A modeling study indicates the Eocene proto-Greenland Sea would also have been characterized by a cyclonic circulation⁴⁷. DS is Denmark Strait. ACEX indicates location of IODP Arctic Coring Expedition. Black dashed line around source areas #42, #43, and #46 shows approximate extent of ice if it extended to the continental divide. Map adapted from a previous publication⁴³. Inset in upper right corner shows paleogeographic map with location of Site 913 in the middle Eocene through early Oligocene¹². The present location of the site is 75°29.356′ N, 6°56.810′ W, and it is estimated to have moved by less than 0.5° in latitude and longitude during the past 45 million years