block stream

Japanese: block stream（英語表記）blockstream

...On gentle slopes, rock masses cannot move and cover the ground surface, forming a block field. On slopes, various phenomena develop, including sliding blocks, where individual rock masses slide slowly, debris slopes, where a large amount of debris creeps and covers the slope as a whole, blockstreams, which are flows of rock masses that accumulate in depressions and flow down, and rock glaciers with ice bodies inside. The phenomena caused by melting and stirring are collectively called frozen soil phenomena.

From Mass Movement

...Also, there are the following types of glacier caused by freezing and thawing. The material on the ground surface is pushed up by frost columns that stand perpendicular to the slope, and as they melt, they fall and sink in the direction of gravity, which causes the glacier to move. The block stream is a block of rock debris that moves down the slope as a unit due to the freezing and thawing of the water contained within it. The rock glacier is a type of glacier that contains ice blocks in the layer of rock debris. These are much faster than other types of glacier, and the largest ones can exceed 1m per year, and each creates its own unique periglacial landform. ...

*Some of the terminology that mentions "block stream" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…緩斜面では岩塊が移動できず，地表をおおって岩石原block fieldをつくる。斜面では個々の岩塊がゆっくり滑る滑動岩塊，多量の岩屑が全体としてクリープし斜面をおおう岩屑斜面，凹所に集積しながら流下する岩塊流blockstream，中に氷体をもつ岩石氷河などが発達する。融凍攪拌作用によるものは凍土現象として一括される。…

【マス･ムーブメント】より

…また，その原因が凍結融解作用によるものに次のようなものがある。地表の物質が斜面に対して垂直に立つ霜柱によって押し上げられ，その融解とともに重力の方向に落下，沈下することによって移動する霜柱匍行frost creep，岩屑の集合体が中に含まれた水の凍結融解によって一体となって斜面を移動する岩塊流block stream，岩屑層の中に氷の塊が存在するものは岩石氷河rock glacierと呼ぶ。これらは他の匍行よりもかなり速く，最大のものは年1mを超えることがあり，それぞれ特有の周氷河地形を形づくる。…

※「block stream」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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