DoggerlandHard to believe that the Thames and the Rhine were once the same river, eh?
“How did the people get there ??”
They walked.
Geologist have found evidence of a land bridge from Europe to UK, from Russia to North America and from Asia to Japan.
They have also found evidence of vineyards in the UK and river beds in the Sahara.
So you mean the climate has changed, it’s gotten hotter then cooler, back and forth long before man introduced fossil fuels and greenhouse gases....you learn something new every day...../sarcasm included....