The generally accepted date for the end of the Younger Dryas and the start of the Pre-Boreal is 11,500 Before Present calibrated.
The start of the period is relatively sharply defined by a rise of 7 °C in 50 years.
The largest predators and humans hunted the mammals of the open tundra.
But it is unclear whether regional variation will allow high-resolution standardization.
Yet, there are some solid dates of the Pre-Boreal and Boreal.
Dates given recently are usually earlier than those given more than 10 years ago.
For example, Iverson (1973) and Rud (1979) give dates of 10,000–9000 BP for the Pre Boreal and 9000–8000 BP for the Boreal, which are uncalibrated C-14 dates based on Scandinavian pollen stratigraphy.
Standardization has become of increasing concern to scientists everywhere.