In the 1970’s I was working as a medic at Prudhoe Bay on Alaska’s North Slope. One of the oil rig drillers told me about a forearm-sized piece of tree branch that came up in the drilling mud from 2000 feet down that had the impression of a vine wrapped tightly around it. That was from a while back. There are no trees above the Arctic Circle at this time although there is driftwood washed west from the Mackenzie River in Canada on the shore of the Arctic Ocean.
Avalanches due to melting ice have buried things deep.
In Antarctica there are fossils showing that it had a temperate climate about 3 and half million years ago. The glacial cap on Antarctica isn't 30 million years old, and none of it has to do with continental drift / plate tectonics.