of glacier © Dr. Kirk Johnson, Denver Museum
of Nature & Science
do we know that ice ages occurred?
that an ice age had occurred in the past was first proposed
by Louis Agassiz in the early 1800s. Agassiz noted that
the slow action of mountain glaciers in Switzerland
produced certain kinds of features in the surrounding
landscape. These include glacial
till and erratics, rock
striations and loess.
He also noted that these features sometimes occurred
in areas far from the mountains, where no glaciers existed.
Based on these observations, Agassiz came up with the
idea that extensive glaciers had existed in the past.
progress since the time of Agassiz has not only confirmed
his idea, but has also begun to reveal a much more detailed
picture of what conditions were like during the last
ice age. To obtain a more detailed picture of the last
ice age, scientists study natural recorders of climate
change, such as fossil pollen, ancient coral reefs,
sediments and ice cores.
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