How do historians know that the bering strait land bridge froze and allowed for the migration into north america?
a.
it’s a theory that is not supported by any concrete evidence.
c.
scientists have found carvings of early civilizations in rocks that have been underwater for thousands of years.
b.
radiocarbon dating of materials in the surrounding area supports the idea.
d.
historians have discovered documents written by these migrants that support facts about their arrival to north america.