The ice caves include inter-locked crevasses covered by snow bridges.
Then the snow bridge had given way, plunging them all to their deaths in the blue-green depths of the glacier.
Nimec stared into the crevasse exposed by the disintegrated snow bridge.
"We believe Joe might have fallen over a snow bridge and was carried downstream," she said.
That will leave a snow bridge over the river, but it won't help any to clear the road.
Moving early in the morning is essential for crossing snow bridges that melt in the midday sun.
"There used to be a snow bridge over there."
Crevasses make travel over glaciers hazardous, especially when they are hidden by fragile snow bridges.
There was a snow bridge across the crevasse, a frail span connecting the two sides.
The danger wasn't the centre of a snow bridge.