I think we're going to have to get used to taking some artistic liberties in our interpretation of the Remnant since there isn't in general too much details on any of the lore. I read from somewhere (might've been a fan made postulate) that Atlas would've been on the northernmost continent. Maybe something between Canada/Scandinavia and Greenland? If you think that starting gradually with intel gathering to get into the mood before throwing people into a mission that would be fine by me too, I could try to see if I could flesh out the situation in Atlas with you while peeps make their posts about finding clues and taking action between the general shenanigans.