Input (grade 13): The Beringian land bridge is believed to have existed both in the glaciation that occurred before 35,000 Before Present (BP) and during the more recent period 22,000-7 ,000 years BP.
Output (grade 12): The Beringian land bridge is believed to have existed both in the glaciation that occurred before 35,000 BP and during the more recent period 22,000-7 ,000 years Before Present.