China - Loess - Belgium
Monday, 19. November 2007, 16:27:57
Talking about flooding. The worst flood in the Yellow River’s history occurred between July and November 1931. About a million people died in the immediate flooding and many more in the ensuing famine and disease, bringing the total casualty figures to around 3.7 million dead.
The heavy sediment load gives rise to regular flooding.
Huang Ho or the Yellow River in China got its name because of yellow loess. Ninety per cent of the sediment load of the Yellow River, the world’s muddiest river, comes from China's loess plateau, the world's largest area of loess, a silt deposit made from an accumulation of dust carried by the wind during the ice ages. Highly consistent, the soil is easy to dig and, with sufficient irrigation, it can become fertile cropland.
Such conditions have traditionally attracted human settlement, and these loess regions were the cradle of Chinese civilisation in very ancient times. A variety of forms of cave dwelling developed here.
Loess, from the German Löss or Löß, and ultimately from Swiss German lösch (loose), is a fine, silty, windblown (eolian) type of unconsolidated deposit. The term also refers to the soil derived from it. Loess is derived from glacial deposits, where glacial activity has ground rocks very fine (rock flour). After drying, these deposits are highly susceptible to wind erosion, and downwind deposits may become very deep, even a hundred metres or more, as in areas of China and the midwestern United States. Loess deposits are geologically unstable by nature, and will erode very readily.
Loess grains are angular, with little polishing or rounding, composed of crystals of quartz, feldspar, mica and other minerals. The particle size is between 1/16+ and 1/32 mm. Because the grains are angular, loess will often stand in banks for many years without slumping. The soil has a characteristic called "vertical cleavage", which makes it easily excavated to form cave dwellings; this is still a popular method of making human habitations in some parts of China.
Loess sediments and their soils cover around one-tenth of the earth. Loess is derived from desert areas or from vegetation free areas around ice sheets. Large loess deposits are in fact found south of the area blanketed by ice during the last Ice Age on the northern hemisphere, and thus not only in China and North America but also in Europe.
A new map showing the distribution of loess sediments in Europe has been published for the first time in 75 years, in digital format. In Europe, loess is a powdery product of glaciations during the Ice Age. During those cold periods, this very fine, light material was swept from bare regions on the edges of the glaciers and deposited in regions with denser vegetation.
Middle Belgium is made up of loess plains and plateaus, and is a very fertile region. Belgium was south of the area covered by ice during the Ice Age. A vegetable called witloof chicory is grown in this area. The vegetable is scarcely known outside Belgium, but is exported to other North European countries in smaller quantities. I ate some at dinner yesterday. I find it fascinating how the climate thousands of years ago still influence our daily life.
• http://www.eurekalert.org/pub_releases/2007-11/haog-nel111507.php
• http://www.physorg.com/news114347085.html
• http://www.scientificblogging.com/news_account/loess_sediments_new_high_resolution_map_shows_europes_best_soil
The heavy sediment load gives rise to regular flooding.
Huang Ho or the Yellow River in China got its name because of yellow loess. Ninety per cent of the sediment load of the Yellow River, the world’s muddiest river, comes from China's loess plateau, the world's largest area of loess, a silt deposit made from an accumulation of dust carried by the wind during the ice ages. Highly consistent, the soil is easy to dig and, with sufficient irrigation, it can become fertile cropland.
Such conditions have traditionally attracted human settlement, and these loess regions were the cradle of Chinese civilisation in very ancient times. A variety of forms of cave dwelling developed here.
Loess, from the German Löss or Löß, and ultimately from Swiss German lösch (loose), is a fine, silty, windblown (eolian) type of unconsolidated deposit. The term also refers to the soil derived from it. Loess is derived from glacial deposits, where glacial activity has ground rocks very fine (rock flour). After drying, these deposits are highly susceptible to wind erosion, and downwind deposits may become very deep, even a hundred metres or more, as in areas of China and the midwestern United States. Loess deposits are geologically unstable by nature, and will erode very readily.
Loess grains are angular, with little polishing or rounding, composed of crystals of quartz, feldspar, mica and other minerals. The particle size is between 1/16+ and 1/32 mm. Because the grains are angular, loess will often stand in banks for many years without slumping. The soil has a characteristic called "vertical cleavage", which makes it easily excavated to form cave dwellings; this is still a popular method of making human habitations in some parts of China.
Loess sediments and their soils cover around one-tenth of the earth. Loess is derived from desert areas or from vegetation free areas around ice sheets. Large loess deposits are in fact found south of the area blanketed by ice during the last Ice Age on the northern hemisphere, and thus not only in China and North America but also in Europe.
A new map showing the distribution of loess sediments in Europe has been published for the first time in 75 years, in digital format. In Europe, loess is a powdery product of glaciations during the Ice Age. During those cold periods, this very fine, light material was swept from bare regions on the edges of the glaciers and deposited in regions with denser vegetation.
Middle Belgium is made up of loess plains and plateaus, and is a very fertile region. Belgium was south of the area covered by ice during the Ice Age. A vegetable called witloof chicory is grown in this area. The vegetable is scarcely known outside Belgium, but is exported to other North European countries in smaller quantities. I ate some at dinner yesterday. I find it fascinating how the climate thousands of years ago still influence our daily life.
• http://www.eurekalert.org/pub_releases/2007-11/haog-nel111507.php
• http://www.physorg.com/news114347085.html
• http://www.scientificblogging.com/news_account/loess_sediments_new_high_resolution_map_shows_europes_best_soil
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