2013 U.S. Go Congress

Mysterious Mima Mounds -Every year, ten thousand people visit Washington’s Mima Mounds Natural Area Preserve to marvel at the many rare plant and animal species living on its 625 acres. Coming into existence over 7000 years ago, it is one of the last remaining wild grass prairies in the Puget Sound. In prehistoric times. These mounds are round or teardrop shaped, and range from eight to 70 feet across, and from one to seven feet high. At one time, the mounds covered 20 square miles. Even now, there are thousands of them, and no one is sure how they came into being. Some people believe that these were Native American burial mounds. However, the local tribes do not have any legends about burying their dead there, and no one has ever found any human remains or tools in any of the mounds. Some traditionalists may still believe that Paul Bunyon created the mounds when he and his Irish laborers dug out the Puget Sound. They dropped the dirt from their wheelbarrow over the Mima Prairie, creating the mounds. Scientists developed several theories about how they formed. Some think a mild, sustained earthquake caused the soils to form the mounds. A soil scientist put soil similar to that of the Mima Prairie on a plywood board and started shaking it, which caused the soil sample to form small mounds. Another scientist measured the way moisture evaporates and saturates soils, called Evapotranspiration. At various times of the year the prairie soils soak with water. As the prairie dries out, the moisture evaporates differently through the various types of soils, causing the mounds. From I-5 Southbound, take exit 95, go west on Highway 121 toward Littlerock. In Littlerock continue west on 128th to the “T.” Turn right on Wadell Creek Road. The Mima Mounds entrance is about one mile ahead, on the left.