Changes of Slope Stability in the Mountains during the Holocene, viewed from Inorganic Content and Decomposition Degree of Peat Deposites.

本文讨论了三个泥炭地的沉积特征。其中一个（Gakinotanbo）位于积雪丰富的日本北部阿尔卑斯山脉，另一个（Okamekie泥炭地和Oodai-ga-hara）位于冬季降雪较少的Kii山脉。结果总结如下：(1)12000年。公元前至8000年。B. p .泥炭开始在Gakinotanbo泥炭地沉积。在这一时期，泥炭地外部频繁发生严重的泥流，这表明8,000年来日本北部地区的斜坡条件不稳定。公元前3-4000年。B. P.Gakinotanbo泥炭地向外扩展，除边缘地区外，泥流的影响减小。这一阶段的开始大致对应于泥炭地泥炭沉积的开始，泥炭地位于日本北部高山带的缓坡上，亚高山带和山地带的山前缓坡上。这一阶段的泥炭层含有大量的木质颗粒，这表明在无雪季节，泥炭层相当干燥，经常发生强降雨。在Gakinotanbo泥炭地，泥流的影响在边缘处也有所减弱，泥炭层已变为欠复合。人们认为，这些变化不仅反映了气温小幅下降造成的融雪延迟，也反映了暴雨发生的减少。这一阶段初期，冬季降雪主要由太平洋沿岸低压带来的奥卡美克泥炭地同步由池塘向泥炭地转变。

In the report, features of deposits at three peatlands are discussed. One(Gakinotanbo)is situated in the snow-rich Northern Japanese Apls, and others(Okamekie peatland and Oodai-ga-hara)are in the Kii Mountains where have a little snowfall in winter season.Results are summerised sa follows :(1)12000yr. B. P. to 8000yr. B. P.Peat began to deposit at the Gakinotanbo Peatland. Severe mudfolws from the outside of the peatland frequently occvred during this period, which suggests unstable slope conditions in the Northern Japanese Apls.(2)8000yr. B. P. to 3-4000yr. B. P.Gakinotanbo Peatland spread to the outside and influences of mudflows decreased except marginal places. Beginning of this stage roughly corresponds to onset of peat deposition in peatlands, located on the gentle slope in the alpine zone and on the gentle piedmont slopes in the subalpine zone and montane zone in the the Northern Japanese Apls. Peat layer of this stage contains many wood particles, which suggest rather dry condition and frequent occurrences of heavy rainfall during the snow-free season.(3)3-4000yr. B. P. to presentAt the Gakinotanbo Peatland, influences of mudflows decreased even at the marginal and peat layer has changed to umdercomposited. Those are considered to have been reflected not only the delay of snow melting caused by the little lowering of temperature, also decrease in occurrences of heavy rainfall.At beginning of this stage, the Okameike peatland where winter snowfall mainly brought by the low pressures along the Pacific coast has changed from the pond to the peatland synchronously.