Loess Hills are located in Western Iowa and Missouri, stretching in a
north south band about 12 miles wide and 300 niles long. They lie a few
miles east of the Missouri river valley. They originated in the repeated
glaciations of the Pleistocene (160,000 to about 11,000 years ago).
After each glaciation as the ice retreated, the Missouri valley was
flooded with meltwater carrying large quantities of silt, which was
deposited in the valley. When the floodwater dried up, so did the
mudbanks. The silt was blown by the wind and deposited on the Loess
Hills. Three glacial ages are recognized in the Loess Hills, and the
total thickness of Loess is about 60 feet.
Loess soil does not contain much clay, so it does not retain water well and is prone to erosion.
The Loess Hills are mostly native forest, wildlife habitat and
grasslands. They have scenic and recreational value, as well as
harboring some unique plant life.
Loess soil covers a fairly large part of Nebraska, so it can be made
fertile. However it is not hugely significant to the US economy.