for scene 35 of the video " Ice Age Wisdom Dunamics - part 1" by Rolf Witzsche - Ice Age Ahead not Global
here for a larger image
Preserved in deep-sea sediments
The climate record that you see here is measured in O-18 ratios that have been preserved in deep-sea sediments in the form of calcite shells produced by microorganisms. Since the calcium carbonate of the shells was formed by combining water and carbon dioxide from water, the organisms have locked into their shells the prevailing ratio of heavy oxygen at the time the organism had lived.
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Published by Cygni Communications Ltd.
North Vancouver, BC, Canada - (C) in public domain - producer Rolf A. F.