- Olivine Bridge Natural Area Preserve (dnr.wa.gov)
This one-of-a-kind site, with its unique geologic formation, represents an example of native vegetation on serpentine soils at low elevations in the western Cascades. Ultramafic rocks such as serpentine (an olive-green, heavy rock) are high in certain minerals such as iron and magnesium, and weather to produce harsh, relatively sterile soils. These soils are typically inhabited by a relatively small number of plant species, some of them specially evolved, that can tolerate these conditions. Dwarfed trees, junipers and serpentine ferns highlight the odd plants, which persist at Olivine Bridge NAP. The 148 acre preserve also supports a mixed conifer forest.