A larger-than-life grasslands soil profile offers an unusual venue to study the serpentine soil complex and explore the foundation of Edgewood’s unique biota. Set against a painted mural, the exhibit tells the above-ground story in terms of the below-ground structure, revealing the geologic composition (iron-magnesium silicates) that created Edgewood’s unique soils. Vastly magnified in the exhibit, the soil profile depicts these silicates, the matrix of Franciscan serpentinite, and the complex root systems of serpentine grassland plants including purple needlegrass, California brome, blue dicks, owl’s clover, tidy tips, and California poppy. These fabricated plants also appear above the ground; a bay checkerspot lights on the owl’s clover; a larva crawls on the dwarf plantain.
A reader railing separates the visitor from the diorama and serves as the mount for two interpretive panels: one on the ecology of serpentine soil complexes and another on the location of serpentine soils at Edgewood with an explanation of how rare flora occur at the site. Serpentinite specimens are mounted on the railing, accessible to touch.