From Diane Winter: (From Rita's question, In the animation, it appears to take less time to go from cold to warm than from warm to cold) The time it takes to go from glacial to interglacial, and the reverse - the oxygen isotope record for the periods in which the polar regions are cooling and ice is growing show that this change happens gradually as compared to the loss of ice and warming interval. The records from Vostok show this well (http://en.wikipedia.org/wiki/File:Ice_Age_Temperature.png). You can see that ice is lost rather rapidly, but takes a while to build back up again. At 2.5 million years ago the cycles were happening more quickly (http://en.wikipedia.org/wiki/File:Five_Myr_Climate_Change.svg), the earth was in the 41ky cycle part of the record.
Emily Cowan: (Rita asks, Was the core in Part 4-5 always under ocean or glacier, not open rock on the surface?) Yes. the drill site was always covered by the sea or an ice sheet. There is a lava flow in the AND-1B core that flowed across the sea floor (it originated underwater not to far away from the drill site). The ash (which is important for dating) probably fell in from the surface - one possibility is that it landed on sea ice and it was released when the ice melted. Volcanologists can tell if the eruption was on land or under the sea by looking at the ash characteristics. Another possibility is that the ash was reworked by waves and currents and deposited as a bed in the sea (that isn't very good for dating the core). We can tell from the characteristics of the deposits that the marine sediments were deposited in deep water below reworking by even big storm waves. There aren't any indications that the deposits were exposed above sea level (no land plants or soil for example).
Emily Cowan: (Rita asks, Was the core in Part 4-5 always under ocean or glacier, not open rock on the surface?) Yes. the drill site was always covered by the sea or an ice sheet. There is a lava flow in the AND-1B core that flowed across the sea floor (it originated underwater not to far away from the drill site). The ash (which is important for dating) probably fell in from the surface - one possibility is that it landed on sea ice and it was released when the ice melted. Volcanologists can tell if the eruption was on land or under the sea by looking at the ash characteristics. Another possibility is that the ash was reworked by waves and currents and deposited as a bed in the sea (that isn't very good for dating the core). We can tell from the characteristics of the deposits that the marine sediments were deposited in deep water below reworking by even big storm waves. There aren't any indications that the deposits were exposed above sea level (no land plants or soil for example).
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