Leftovers from a big avalanche
The road to Milford Sound used to be shut for about 4 months of the year until they started a management program where they set off explosives to cause avalanches of a manageable size which can then be cleared manually. This was one which had been set off 4 weeks earlier. When the avalanches are set off there's still a lot of snow. This remnant had been thawing out for 4 weeks in temperatures of 15-20 degrees!
