Observations on perennial snow patches after winter with small amount of snowfall

In the ablation season of 1979 after winter with small amount of snowfall, observations were carried out on the following perennial snow patches formed by avalanche debris; Ishikorobi-zawa perennial snow patch (37°53’N, 139°39’E) at 1080m above sea level in the Iide mountain range, Kuwanoki-zawa Perennial snow patch (37°09′N, 139°05’E) at 800m above sea level in the Echigo mountain range and Shirouma perennial snow patch (36°45′N, 137°46′E) at 1780m above sea level in the Northern Japan Alps. The obtained resuIts were as follows. (1) The snow patch formed by avalanche debris diminishes considerably by the partial collapses as the result of the development of a tunnel underneath. (2) Ishikorobi-zawa perennial snow patch at the end of the ablation season consisted of four snow (ice) layers, the oldest of which was estimated to accumulate in winter of 1975-76. Then the snow patch remained as several pieces of snow blocks at a distance of about 200m along the valley. (3) Kuwanoki-zawa perennial snow patch on 1 September consisted of four snow (ice) layers, the oldest of which was estimated to accumulate in winter of 1975-76. The snow patch was melted completely by middle of October. By the meteorological date, the snow patch was estimated to melt completely within about ten years period. (4) Shirouma perennial snow patch at the end of the ablation season consisted of nine snow (ice) layers, the oldest of which was estimated to accumulate in winter of 1970-71. The area of the snow patch remaining then was at a distance of about 800m along the valley