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This dataset documents the location and characteristics of 185 exotic tundra boulders found on the North Slope of Alaska, spanning observations from 1826 to 2025. These boulders—scattered across coastal tundra, estuarine margins, and barrier islands—represent a persistent but enigmatic feature of the Arctic landscape. Their lithologies, which include granite, quartzite, diabase, dolomite, chert, and gneiss, are exotic to the region and are widely interpreted to be ice-rafted debris deposited during Pleistocene highstands of the Arctic Ocean. Spatial and lithologic patterns suggest an origin in the Canadian Arctic Archipelago and Mackenzie River basin, transported westward by sea ice or icebergs during glacial periods. The dataset integrates georeferenced boulder locations from early exploration accounts (e.g., Leffingwell 1919; Stefansson 1910, Franklin and Richardson 1828), mid-century field surveys (MacCarthy 1958), geologic interpretations of offshore facies and provenance (Rodeick 1979) and USGS (U.S. Geological Survey) engineering geological maps (1980s), and modern field observations from the 2000s–2020s. Boulder characteristics—such as lithology, surface striations, and faceting—are included where available. These observations contribute to understanding of likely saline permafrost distribution, Arctic coastal dynamics, sea-level history, and the paleogeography of iceberg and sea-ice transport. They also provide a rare terrestrial window into ice-rafted sedimentation processes typically studied in marine environments. All data are curated in a comma separated spreadsheet with associated metadata to support future geomorphological, paleoclimatic, and sea-level modeling studies. The complete list of references is provided below: Barnes, P.W., 1982. Marine Ice-Pushed Boulder Ridge, Beaufort Sea, Alaska. ARCTIC 35, 312–316. https://doi.org/10.14430/arctic2330 Brigham, O.K., 1985. Marine stratigraphy and aaino-acid geochronology of the Gublk Fomatlon, western Arctic Coastal Plain, Alaska. USGS Open File Report 381. Dease, P.W., Simpson, T., 1838. An Account of the Recent Arctic Discoveries by Messrs. Dease and T. Simpson. The Journal of the Royal Geographical Society of London 8, 213–225. Franklin, J., Richardson, J., 1828. Narrative of a Second Expedition to the Shores of the Polar Sea, in the Years 1825, 1826, and 1827. Carey, Lea and Carey. Gibbs, A.E., Richmond, B.M., 2009. Oblique aerial photography of the Arctic coast of Alaska, Nulavik to Demarcation Point, August 7-10, 2006. US Geological Survey. Hopkins, D.M., Hartz, R.W., 1978. Coastal morphology, coastal erosion, and barrier islands of the Beaufort Sea, Alaska. US Geological Survey,. Jorgenson, M.T., 2011. Coastal region of northern Alaska, Guidebook to permafrost and related features (No.GB 10). Alaska Division of Geological and Geophysical Surveys. https://doi.org/10.14509/22762 McCarthy, G.R., 1958. Glacial Boulders on the Arctic Coast of Alaska. ARCTIC 11, 70–85. https://doi.org/10.14430/arctic3734 Naidu, A., Mowatt, T., 1992. Origin of gravels from the southern coast and continental shelf of the Beaufort Sea, Arctic Alaska, in: 1992 International Conference on Arctic Margins Proceedings Programs with Abstracts. pp. 351–356. O’Sullivan, J.B., 1961. Quaternary geology of the Arctic Coastal Plain, northern Alaska: Ames, Iowa, Iowa State University of Science and Technology, Ph.D. dissertation, 191 p., illust., maps. Iowa State University. Rawlinson, S.E., 1993. Surficial geology and morphology of the Alaskan central Arctic Coastal Plain (No. RI 93-1). Alaska Division of Geological and Geophysical Surveys. https://doi.org/10.14509/2484 Reimnitz, E., Ross, R., 1979. Lag deposits of boulders in Stefansson Sound, Beaufort Sea, Alaska (No.79–1205), Open-File Report. U.S. Geological Survey,. https://doi.org/10.3133/ofr791205 Rodeick, C.A., 1979. The origin, distribution, and depositional history of gravel deposits on the Beaufort Sea Continental Shelf, Alaska (No. 79–234), Open-File Report. U.S. Geological Survey,. https://doi.org/10.3133/ofr79234 Schrader, F.C., Peters, W.J., 1904. A reconnaissance in northern Alaska across the Rocky Mountains, along Koyukuk, John, Anaktuvuk, and Colville Rivers, and the Arctic coast to Cape Lisburne, in 1901, with notes (USGS Numbered Series No. 20), Professional Paper. U.S. Geological Survey, Washington, D.C. https://doi.org/10.3133/pp20 Simpson, 1855. Observations on the western Esquimaux and the country they inhabit?: from notes taken during two years at Point Barrow | CiNii Research [WWW Document]. URL https://cir.nii.ac.jp/crid/1130000795332231552 (accessed 6.10.23). Smith, P.S., Mertie, J.B., 1930. Geology and mineral resources of northwestern Alaska. USGS Report 1. Stefansson, V., 1910. Notes from the Arctic. Am. Geogr. SOC. Bull 42, 460–1. Williams, J.R., 1983. Engineering-geologic maps of northern Alaska, Wainwright quadrangle (No. 83–457), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr83458 Williams, J.R., Carter, L.D., 1984. Engineering-geologic maps of northern Alaska, Barrow quadrangle (No.84–124), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr84126 Williams, R.J., 1983. Engineering-geologic maps of northern Alaska, Meade River quadrangle (No. 83–294), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr83325 Wolf, S.C., Reimnitz, E., Barnes, P.W., 1985. Pleistocene and Holocene seismic stratigraphy between the Canning River and Prudhoe Bay, Beaufort Sea, Alaska. US Geological Survey,. de Koven Leffingwell, E., 1908. Flaxman Island, a Glacial Remnant. The Journal of Geology 16, 56–63. https://doi.org/10.1086/621490 de Koven Leffingwell, E., 1919. The Canning river region, northern Alaska (No. 109). US Government Printing Office. 

Abstract. Sometime during the middle to late Holocene (8.2 ka to ∼ 1850–1900 CE), the Greenland Ice Sheet (GrIS) was smaller than its currentconfiguration. Determining the exact dimensions of the Holocene ice-sheetminimum and the duration that the ice margin rested inboard of its currentposition remains challenging. Contemporary retreat of the GrIS from itshistorical maximum extent in southwestern Greenland is exposing a landscapethat holds clues regarding the configuration and timing of past ice-sheetminima. To quantify the duration of the time the GrIS margin was near itsmodern extent we develop a new technique for Greenland that utilizes in situcosmogenic 10Be–14C–26Al in bedrock samples that have becomeice-free only in the last few decades due to the retreating ice-sheet margin atKangiata Nunaata Sermia (n=12 sites, 36 measurements; KNS), southwest Greenland. To maximizethe utility of this approach, we refine the deglaciation history of the regionwith stand-alone 10Be measurements (n=49) and traditional 14C agesfrom sedimentary deposits contained in proglacial–threshold lakes. We combineour reconstructed ice-margin history in the KNS region with additionalgeologic records from southwestern Greenland and recent model simulations ofGrIS change to constrain the timing of the GrIS minimum in southwestGreenland and the magnitude of Holocene inland GrIS retreat, as well as to explore theregional climate history influencing Holocene ice-sheet behavior. Our10Be–14C–26Al measurements reveal that (1) KNS retreated behindits modern margin just before 10 ka, but it likely stabilized near thepresent GrIS margin for several thousand years before retreating fartherinland, and (2) pre-Holocene 10Be detected in several of our sample sitesis most easily explained by several thousand years of surface exposure duringthe last interglaciation. Moreover, our new results indicate that the minimumextent of the GrIS likely occurred after ∼5 ka, and the GrISmargin may have approached its eventual historical maximum extent as early as∼2 ka. Recent simulations of GrIS change are able to match thegeologic record of ice-sheet change in regions dominated by surface massbalance, but they produce a poorer model–data fit in areas influenced by oceanicand dynamic processes. Simulations that achieve the best model–data fitsuggest that inland retreat of the ice margin driven by early to middleHolocene warmth may have been mitigated by increased precipitation. Triple10Be–14C–26Al measurements in recently deglaciated bedrockprovide a new tool to help decipher the duration of smaller-than-present iceover multiple timescales. Modern retreat of the GrIS margin in southwestGreenland is revealing a bedrock landscape that was also exposed during themigration of the GrIS margin towards its Holocene minimum extent, but it has yetto tap into a landscape that remained ice-covered throughout the entireHolocene.