It's 'stone cold'. Stone has a much higher density than earth, takes more warmth (calories) to bring it above freezing than the surrounding dirt ? That's my quasi-scientific, low technology guess.
That's some beautiful pictures, but I'm sure glad we don't get that kind of snow where we live. And if you think Beaver Creek, MI, is close to the middle of nowhere, you ought to visit Beaver Creek, YT, Canada, that I've passed through a few times.