85.冰川周期 TW: ice ages 1.kwo:冰川周期原因(old)Earth sways while orbiting the Sun, causing fluctuationsin the intensity of sunlight reaching the Northern Hemisphere aw+: JIàkwo support: oxygen isotopes contained in shellsdeposited many thousands of years ago 2.kwn: 冰川周期原因(new)complex interactions among oceans, ice sheets, and atmosphere aw-: kwo-independently of the orbital cycles 3.kw3: difference due to geographical variations in climate and differences between marine andfreshwater studies aw+: JIàkwo
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