14. Over the last 650,000 years, climate conditions changed repeatedly from interglacial warm periods, through gradual cooling and build up of glacial ice, to cold periods of a glacial maximum. Which one of the following statements about the glacial-interglacial cycles is correct? a) There have been 4 glacial-interglacial cycles during the Pleistocene. b) At the height of the last glacial cycle 18,000 years ago, sea levels were approximately 100 m lower than today. c) During the interglacials, ice sheets advanced to cover all of Canada. d) At a glacial maximum, glacial ice was less than 100 m thick over central Canada and Hudson Bay.
