Just a small note to my comments above.

Glaciologists study the rate at which ice flows in different places. It flows at different rates in different places. The climate is different in different places. Scientists are aware of these rates when they drill ice cores. I suggest before SoSick makes off-the-cuff comments about glacial flow rate in the Himalayas, that she actually look up some information about this. My relative spends months every summer studying flow rates in Iceland, among other things. It's pretty funny that you think you're just as qualified to tell her she's dead wrong.

Your own source about the Alaskan glaciers, CTD, said most are quite young, not all. This is why Alaskan ice cores from some select areas show a climatic record dating back one or two thousand years. And why scientists understand that they would not be able to obtain dates from there which are older than this. Ice cores from Antarctica and China, however, have been dated to several hundred thousand years before the present. The article I linked to earlier explains some of the dating methods that are used, and a general search including Wikipedia will provide information too.

This is all very interesting, but the question remains: why do dates from ice cores, varves, and tree rings agree? If you think you've "debunked" one, then what about the others?