The Nature Conservancy manages this magnificent plateau overlooking the Columbia River. Home to spectacular spring wildflower displays, the Preserve is so diverse partly because it lies in the transition zone between the moist, heavily-forested west side of the Cascades and the drier bunchgrass prairies of the east. The geology of the plateau is also intriguing. Lava flows, catastrophic floods and volcanic ash deposits shaped a mound-and-swale topography that perplexes the experts. Earthquake sorting, freezing and thawing, erosion, soil accumulations by plants and wildlife burrowing activities have all been suggested as having caused the mounds.