Earth’s glacial record

Dropstone structures are among the most telling indicators of former glaciation, in this case Late Proterozoic glaciation in Namibia. Dropstones are formed when icebergs release debris into laminated sediments of the sea or lake floor. These dropstones near Narachaamspos in the Kaokoveld have been used to promote the ‘Snowball Earth’ hypothesis as a global refrigeration event, while the overlying pink and orange carbonate rocks are indicative of the succeeding hot phase. MH

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