论文部分内容阅读
在非洲南部纳米比亚的荒漠草原上,有一种被当地人称为“仙女圈”的神秘怪圈不断地形成又不断消失,迄今没有人知道原因。这种怪圈只在含石极少的沙质土壤上才会形成,在不移动的沙丘或冲积扇上却未见到。“仙女圈”多出现在偏僻地方。由沙壤裸点形成的“仙女圈”大小为直径2~12米。小圈可存续超过20年,较大圈的“寿命”甚至达到75年。这些怪圈在草原中自然形成,圈内杂草不生,维持原貌多年后又不知何故地消失。
In the desert steppes of Namibia in southern Africa, there is a mysterious circle of locals called “fairy circle” constantly formed and disappear, so far no one knows the reason. This kind of cycle is formed only on sandy soil with very little rock, but it is not seen on the non-moving dunes or alluvial fans. “Fairy ring ” appear in remote areas. The “fairy circle” formed by the bare spots of the sand soil is 2 to 12 meters in diameter. Small circle can survive for more than 20 years, the larger circle “life ” even reached 75 years. These strange circles are naturally formed in the grasslands, the weeds are not born, to maintain the original appearance after some years and somehow disappear.