An examination of mineral deposits in a coastal cave on the Spanish island of Mallorca shows evidence of rapid rises and declines in sea level as the planet warmed and cooled. Reporting in the journal Science, University of Iowa researchers said that studies of the mineral, calcite — deposited by sea water on the inside of a seaside cave, like rings on a bathtub — showed that roughly 81,000 years ago sea levels jumped by more than 6 feet a century during a warm period, and then dropped during a subsequent cooling cycle at a similar rate — 66 feet per 1,000 years.