While most researchers now use this late-13th-century date, others are revising it upward even further to around 1320 AD or later, based on new evidence from moa egg shells and from the Kaharoa eruption of Mount Tarawera (1314 ±6 AD), whose tephra forms a geological layer below all well-dated human and rat sites. Some researchers now conclude that the weight of all the radiocarbon and DNA evidence points to New Zealand having been settled rapidly in a mass migration sometime after the Tarawera eruption, somewhere in the decades between 1320 and 1350 CE - which suggests that the Great Fleet theory, and the genealogical calculations on which it was based, were not totally inaccurate after all.