loess hills

Hills made of loess. Formations of such hills are uncommon;
One formation is located in western Iowa, and common knowledge holds that another lies on the banks of the yangtze river in China, though the author cannot confirm this.

Loess hills were formed in recent ice ages - ice picked up dirt from areas to the north, and ground it into fine sandy soil. It was deposited wherever the ice melted. In areas with loess hills, it was deposited in large quantities.