Thanks for your thoughts Lingon, much food for thought.

I should have said that the impact is indeed a long time ago, never really fixed a time frame as the the impact idea has only come up recently to help explain the rough world map i envisioned years ago.

I can certainly downsize the impact size. Ive just been toying with distances based of the maps ive done. And also the far left continent had a ala pilgrims/mayflower kinda trip to the east continent 100's of yrs ago so im pegging a kinda 5000km kinda trip.