Suggested causes of ice age periods include the positions of the continents, variations in the Earth's orbit, changes in the solar output, and Vulcanism.
导致冰河期形成的可能原因包括：大陆的位置，地球轨迹的变化，太阳辐射的输出，以及火山的作用。
2
What the Vulcanism of the Cascade Mountains tells you is that this range not only has active subduction beneath it, but that the rock layer riding on top is thin.
一连串的火山山脉告诉你的是，这个山脉不仅底下有活跃的俯冲活动，而且上面的岩石层也很薄。
3
According to paleobiologist Jessica Whiteside of Brown University, a leading researcher on end-Triassic vulcanism, more evidence is needed before Ruhl’s interpretations are conclusively supported.