It was a period of cyclical climate change, including several ice ages in high and mid-latitudes, cycles of varying aridity and humidity in low latitudes, and significant fluctuations in sea level.

• 它是气候周期性变化的一段时期，包括高、中纬度地区的几个冰期,低纬度地区干湿周期性的改变，海平面明显的波动。