Towards the end of each glacial period and into the begining of the following interglacial period, there is a 12,500 year interval when the sea level of the Bering Sea has dropped low enough to expose the continental shelf between Asia and North America. This exposed sea bed is rich with nutrients from decomposed sea life, and permits the growth of mosses and lichens soon after it rises out of the sea. The land thus formed is called the Bering Land Bridge, and it remains viable for many thousands of years before it sinks below the waves due to the rising sea levels later in the interglacial period.

Today there are glaciers in Southern British Columbia, Canada, that are the remnants of the great continental ice sheet of the last glacial period called the Wisconsin.