Two different dates have been offered as the approximate end point of the last ice age in North America. The first date was established by testing insect fragments found in samples of sediments to determine when warmth-adapted open-ground beetles replaced cold-adapted arctic beetles. The second date was established by testing pollen grains in those same samples to determine when ice masses yielded to spruce forests. The first date is more than 500 years earlier than the second.
Toward the end of the ice age, warmth-adapted open-ground beetles colonized the new terrain opened to them faster than soil changes and seed dispersion established new spruce forests most strongly supports the conclusion about the last ice age and its aftermath in North America if the statements above are true.