Just about any kid looking out on acres of a weirdly pimpled landscape is inevitably going to ask the question: How did these mounds get here?
A new cartoon book offers possible answers to that question as it explores the various creation ideas behind one of Washington state's enduring geologic mysteries, the Mima Mounds.
Mima Mounds have been described as soil pimples, the skin of a basketball, a ski slope of dirt moguls and more. The hills of silt, sand and pebbles can reach seven feet in height and up to 40 feet across.
Best seen at Mima Mounds Natural Area Preserve near the town of Littlerock, other sites are scattered across the South Sound. Similar groupings of mounds found in other locations nationwide are called Mima-like mounds.
By itself, a Mima mound is a featureless pile of dirt. But, you'll seldom see one alone, and that's what makes them special. Dozens, hundreds, thousands of the hills group together, all keeping a relatively consistent yet tight distance from each.
So far, scientists have not conclusively proven how they were formed.
Out this week, the free "Guide to the Mima Mounds" by the state Department of Natural Resources is a 28-page educational publication that looks at the numerous ideas put out since the 1800s.
The book, narrated by Goodwin the Gopher, takes a look at those possible sources which include:
• Glaciers that moved across the area 16,000 years ago.
• Seismic activity that shook soils into hills.
• Tree roots that retained soil.
• Gophers which created super mounds over generations.
Stories from the local Chehalis Tribe tell of a great flood that swept the area and created the mounds.
Don't expect any conclusion in the book. For now, Washington is holding on to one of its best kept secrets.
The book can be downloaded here: https://www.dnr.wa.gov/publications/ger_mima_mounds_booklet.pdf.