How
the Loess Hills Were Formed
Twelve to thirty
thousand years ago glaciers were moving and melting over parts
of the Iowa landscape and the states to the north. Due to changes
in temperature, the front of the glaciers would melt in the
summer and huge amounts of meltwater would flow down the Missouri
River valley. |
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| In the wintertime,
the glaciers stopped melting. The flow of water into the rivers
slowed down significantly. This exposed sandbars and silt material
on the floor of the valley. |
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Wind
Creates Hills
Winds from the west were very strong during these times and
they would whip through the Missouri River valley, pick up the
exposed silt material and deposit it on the east side of the
valley. This cycle was repeated over thousands of winters until
about twelve thousand years ago. |
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| The glaciers disappeared
and the wind diminished. The Loess Hills of Iowa remained. As
time marched on, water carved the hills by eroding the silt.
Creeks and rivers, fed by rainwater and snowmelt, rushed down
the slopes, creating most of the distinctive shapes of the Loess
Hills that we see today. |
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