I think 1991 it was the fall of soviet union
Uniformitarianism
fossils
radioactive decay
48 million
after
The youngest age of the shale is 910 ka. According to the principle of inclusions, the shale formed before the tephra, so the tephra must be younger than 910 ka.
Then it is moving towards earth
It depends on the mass of the ice,temperature around it and latent heat energy required to melt the ice.
However the furthest a ice berg can travel is estimately 32-40°n/s
