As you may have noticed, there is a growing body of evidence saying that people came to the Americas long before an ice-free corridor opened in the ice sheets of Canada. Well, a new study of sediment cores identified two intervals that would have supported early human migration to North America, thanks to favorable ice and ocean conditions. The sediment cores showed that during the periods of 22,000-24,500 BP and 14,800-16,400 BP, sea ice was present in the winter, which may have given people a chance to travel along the coast. According to Summer Praetorius, “Sea ice is relatively flat and pretty stable when it is stuck to the shoreline, so you can walk on the ice and hunt seals to survive through the winter. It seems possible that sea ice could have facilitated movement, rather than hinder it, by providing a more traversable surface than the hazardous pathway of crevassed glaciers or paddling against strong ocean currents.” These findings back the existing (and growing) theory that people followed a Pacific coastal route as they headed south. And it’s worth noting that meltwater from the Cordilleran ice sheet would have accelerated ocean currents moving north, making boat travel difficult, which is why they believe these people made the trip by foot.