Issues

COVER: Margin of the Greenland Ice Sheet in the exposed foreland in Inglefield Land, northwestern Greenland. Multiple detrital impact melt rocks were retrieved at this and other locations along the ice wall or within glaciofluvial channels, all recently emerged from under the ice. All but one of the radiometrically dated samples record a Late Paleocene impact event attributed to the proximal 31-km-wide Hiawatha Impact Structure; however, a single pebble-sized sample contains evidence of a second, ancient hypervelocity impact event that occurred in the Paleoproterozoic, around one billion years ago. (Coordinates: 78.58920, –66.81570, looking north.) See “Evidence for ca. 1 Ga hypervelocity impact event found in northwest Greenland,” by William Hyde et al., p. 517–521..

Photo by Pierre Beck