The pattern of the modern distribution might be unduc-ed by the influence of the glacial epoch during the Quaternary Period. 现代分布状况可能是受第四纪冰期的影响而造成的。
Stratospheric ice clouds promoted the destruction of ozone radiation shielding of the Earth resulting in biotic catastrophes which usually follow the glacial periods. 平流层冰云促进了对臭氧辐射盾牌的破坏，从而导致继冰期之后的生物灾难。
They are typical geological remains from the Glacial Age. 是典型的冰川期地质遗迹。
