Comparison of a geologic cross section across Upheaval Dome (top) and an idealized cartoon of a complex meteorite impact crater (bottom). Except for a few “shocked” quartz grains, no impact-crater-formed rocks have been found at Upheaval Dome, evidently because they were removed by erosion. Geologic profile modified from Jackson and others (1998, Geological Society of America Bulletin); impact crater cartoon from NASA Web site.