Large boulders along the trail are hard blocks of the Franciscan Complex melange. The first has a tilted flat surface with crystals of green and silver with red dots. The grass green crystals are omphacite pyroxene, with silver flaky muscovite mica pockmarked by red garnets. The next block in the path below is blueschist a metamorphic rock containing a blue amphibole, glaucophane or lawsonite, as the principle mineral. The green and blue streaks are alternating layers of blueschist and eclogite.
Streaks come from flow in solid rock which occurred under intense squeezing in the subduction zone .
This is metamorphic foliation, so called because of the layers formed during flow by the flat or platy minerals that line up parallel to flow. The ridge to the left of the trail is light green clay with dark green fragments of shiny serpentine embedded in it. Serpentine forms when very iron-rich rocks of the mantle combine with hot water. These fluids change olivene to serpentine. Slick surfaces are polish formed by shear in fault zones.