At Mt. Yatsugatake and its environs, a few species of Picea are now isolated in distribution, though their fossils are found widely in the Early and Middle Pleistocene deposits. The author studied the pollen floras from the three peat beds, i. e. the Nakamura-Peat Bed-1, 2 and 3, developed at the western foot of Mt. Yatsugatake, and made some considerations on the vegetations and climates of those times. The age of the three peat beds, according to the radiocarbon dating, is early Würm Glacial. The results are summarized as follows. 1) Conifer forests were dominant in those days, that were composed mainly of such genera as Picea, Pinus (Haploxylon), Abies and Tsuga. But some broadleaved trees were also thriving, though they are growing today in the mountain zone. These vegetations correspond roughly to those found today in the altitudes from 1, 300m to 1, 700m above sea level at Mt. Yatsugatake. The annual mean temperature of those days is estimated about two to four degrees lower in centigrade than that of today. Precipitation is considered to have been rather small being similar to that of today. 2) No trace of reconstruction of forests after destruction by pumice flows is discerned in the constitution of the pollen floras. And, no transition nor difference of vegetations are recognized clearly among the pollen floras of these three peat beds. 3) Present distribution of Picea maximowiczii, now concentrated in and around Mt. Yatsugatake, is the result of reduction of the same species of the Late Pleistocene. The limited distribution of Picea shirasawae and P. koyamai is also explained by the same kind of reducing process as that of Picea maximowiczii.
It is the main interest of this paper how amorphous matters of humic horizon had changed on burial. Samples from several buried humic horizons among the Upper Member of Ashitaka “Loam” Formation, about 14, 000-30, 000 years old, were studied in comparison with those from the recent humic soils lying on them. The followings were obtained from determination of apparent and if possible net charges of allophane, humus, and layer-silicates, and from extraction of free oxydes with hydrogen peroxyde diggestion and sodium bicarbonate-sodium citrate-sodium dithionite treatment. 1) Contents of allophane and amorphous sesquioxydes extracted with the last mentioned treatment are abundant and uniform through the profile. 2) Activities measured of alumina both free and of allophane decrease with depth. 3) Apparent and net activities of humus also diminish continuously with progressive burial, the former falling even into zero level in the lowest horizons. 4) Gibbsite formation found its maximum phase in the upper horizons. 5) Relative abundance of silica took place in the lower horizons, thus resulting in formation of halloysite and decrease in net positive activity of allophane.