Tom, I searched a ton of relevant terms, and couldn't find the evidence of a 60 000 mile long wall of ice mentioned in the book. Am I just a terrible searcher?
Edit: Well, the closest I found was:
"Proceeding to the westward, they discovered and sailed about sixty miles along a solid wall of ice one hundred and fifty feet high, which he, believing to be a covering or crust of a more solid base, named "Cote Clairee." ...but the weakly condition of his crews imperatively demanded of him to discontinue their laburious exertions..."
Pg 114