Figure 24. Tephra set S at the Muddy River quarry site about 11 km east of Mount St. Helens. The gray color of the coarse ash and lapilli of layer Sw contrasts with the yellow and brown colors of other parts of the set. Only a few centimeters of the lower part of layer So are present above layer Sg; the remainder of layer So has been mixed into an overlying oxidized, ash-rich deposit by soil-zone processes. Pocketknife shown for scale. Photograph taken in 1979.