A bit more detail here including picture of the "data" (i.e. metal film cans): http://nsidc.org/monthlyhighlights/2013/04/glimpses-of-sea-ice-past/ http://nsid

A bit more detail here including picture of the "data" (i.e. metal film cans): http://nsidc.org/monthlyhighlights/2013/04/glimpses-of-sea-ice-past/ http://nsidc.org/monthlyhighlights/2013/04/glimpses-of-sea-i... Which linked to this paper in the journal "The Cryosphere": http://www.the-cryosphere.net/7/699/2013/tc-7-699-2013.pdf http://www.the-cryosphere.net/7/699/2013/tc-7-699-2013.pdf