I'm thinking there may be no definitive grounding line hereabouts, sure it's grounded either side to some extent, but in the main channel there may be contact in places, and possibly not. I suspect the large peices that didn't overturn may be the deepest/thickest, it's a pity the new bed elevation doesn't extend further west, which could give us a clue to the thickness of the ice stream when/if these peices get stuck. Curiously looking at the behaviour of the ice stream my guess was that the deep saline water was likely continuous below 750m and probably not so much above 600m where there's enough ice to displace it, that would work with ice 900m thick. So if they pass the inner cills, unless it's very warm they won't pass the outer cill for a whle, we'll see.