While exploring their grandfather's farm, Max and Hannah discover hundreds of round rocks piled up in the corner of a field. The children seek out Grandpa to learn how the rocks got there and why the rocks are round. The Mystery of the Round Rocks explores part of the geological history of South Dakota. The story begins with huge mountains and vast glaciers that form rivers and thousands of small round rocks. Along the way, watch out for saber-toothed tigers, woolly mammoths, and short-faced bears.

Illustrated by: Jason Folkerts