The mirage is produced by refraction and is intensified by the columns of comparatively warm air rising from several cracks and leads that have opened eight to twenty miles away north and south." We noticed this day that a considerable change had taken place in our position relative to the Rampart Berg.

It appeared that a big lead had opened and that there had been some differential movement of the pack.
The opening movement might presage renewed pressure.

A few hours later the dog teams, returning from exercise, crossed a narrow crack that had appeared ahead of the ship.

This crack opened quickly to 60 ft.

and would have given us trouble if the dogs had been left on the wrong side.