Figure 27. Coarse pumice layers of tephra set J about 8 km east of the central vent of Mount St. Helens. Most of layer Jb here has been disturbed by near-surface processes. Locally, the deposit of colluvium and wind-blown material above layer Jb contains identifiable lenses of ash from Mount Mazama. Pocketknife shown for scale. Photograph taken in 1983.