The islands have been shaped by numerous glaciations during the Quaternary Period, the most recent being the Devensian.[citation needed] As this ended, the central Irish Sea was deglaciated and the English Channel flooded, with sea levels rising to current levels some <answer>4,000 to 5,000 years ago</answer>, leaving the British Isles in their current form. Whether or not there was a land bridge between Great Britain and Ireland at this time is somewhat disputed, though there was certainly a single ice sheet covering the entire sea.
When did sea levels reach their current highth?
4,000 to 5,000 years ago