Could ice still be lurking within the rock glaciers of the Yari-Hodaka ridge?
If you don't know what you're looking for, you'll certainly miss it. This applies as much in the Japan Alps as anywhere. When I traversed over Naka-dake, on my way towards Yari, I must have walked right by it. Perhaps even over it. Cloud could have been an extenuating factor but ignorance was the main barrier to seeing what was right under my feet.
Could these rock glaciers still be alive? On the face of it, the chances seem slim. Hotter summers in the Japan Alps mean that permafrost couldn't exist below 2,800 metres, which is hardly lower than the highest ridgelines. And none has been found in this area.
But one researcher holds out hope for "probable permafrost occurrence within several rock glaciers". Perhaps that's enough ice to make them, if not true glaciers, then ghosts of glaciers past.
Shimizu Chōsei, Hyakumeizan no Shizengaku (Nishi-Nihon), Kokon Shoin 2002 (for photo of Nakadake rock glacier)
Aoyama, M, Permafrost environment in the Yari-Hotaka Mountains, southern part of the Northern Japanese Alps, in Proceedings of the 8th International Conference on Permafrost, 2003