ABSTRACT. Polished and rounded grains of quartz, secondary quartz and chert have been found in loess and peat in interior Alaska. The intermediate diameter of these polished and rounded grains is between 35 and 0.07 mm., with grains of 0.7 mm., 2 to 4 mm. and perhaps 10 to 20 mm. being most abundant. Polish on these grains has been produced by abrasion in bird gizzards. Gizzard-bearing birds are living in interior Alaska today and produce glossy polish on their gastroliths comparable to the polish on gastroliths from the Holocene and Pleistocene deposits. The polish and roundness of Recent bird gastroliths vary, being more pronounced in those of living birds in late winter. Some of the Holocene and Pleistocene polished gastroliths are believed to have been produced by species of birds not now living in interior Alaska, because modal size classes of these ancient gastroliths do not coincide with modal size classes of polished gastroliths from birds living there today.
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