GLACIAL LANDFORMS ON THE NORTHERN SLOPES OF MT. KITA-HOTAKA

Abstract

In this paper, glacial eroded landforms on the northern slopes of Mt. Kita-Hotaka are reported on the basis of the new data from the author's surveys in July and Sept. 1950. 1) The glacier which formed “Okiretto Cirque” may have been consisted of two cirque glaciers, stream-directions of which were contrary to each other, that is, one to the south, and the other to the north. 2) The author found out two cirques on the northern slope of the Eastern Ridge of Mt. Kita-Hotaka and they stand side by side with the southern part of Okirreto Cirque. 3) One of them has been formed on a terrace-like even landform at 2700m. alt. just below the top of Mt. Kita-Hotaka. Its cirque wall is called “Northern Buttress, ” and the moraine lies east to west in a straight line. 4) The other is in further east, and its cirque bottom is at 2400m. alt.. There is a series of roche moutonne over the top part of the valley wall of Hidari-mata Valley, and, among folds of roche moutonne, six small traps are scattered one by one. These rock faces are perfectly scoured by glacial erosion, and we can point out many flutings there. Except this place, a series of roche moutonue having completely scoured face is reported only from “Tengu-bara Cirque” in the Japan Alps. The cirque bottom, which is not filled up by taluses developing from cirque walls, shows perfectly reversed slope caused by glacial deepening action that has no report in Japan up to present time, 5) Okirreto, 2700m. alt., is the only lowest part in the Yari-Hotaka main ridge, and a cause of this topography may have been due rather to the presence of even lower landforms before glacial time than to the result of glacial erosion. It is supposed that glacial action in this vicinity were in effect on the even topography having stretched with the altitude of 2400-2700m. before glacial period. 6) We can suppose two glacial periods from the distribution of moraines in the Okirreto Cirque, they, however, may have been equal to substages in one glacial age in Europe or N. America. 7) These glacial features are rather fresh, and the degree of destruction of them is still imperfect, but moraines are stained by limonite on the surface.