Figure 7

Figure 7. Tephra set C along USFS Road 25 about 17 km southeast of Mount St. Helens (measured section C-1). The oldest tephra recognized here consists of about 100 cm of layer Cb, which overlies 50-100 cm of brown colluvium, which in turn overlies bedrock. Layer Cb is overlain successively by (1) pale layer Cw, (2) dark ash, and (3) pale layer Cm. About 200 cm of ash that includes thin tephra beds among thicker ash-cloud deposits separates layer Cm from the coarse layer Cy at the top of the set. Shovel handle is about 50 cm long. Photograph taken in 1986.Figure 7. Tephra set C along USFS Road 25 about 17 km southeast of Mount St. Helens (measured section C-1). The oldest tephra recognized here consists of about 100 cm of layer Cb, which overlies 50-100 cm of brown colluvium, which in turn overlies bedrock. Layer Cb is overlain successively by (1) pale layer Cw, (2) dark ash, and (3) pale layer Cm. About 200 cm of ash that includes thin tephra beds among thicker ash-cloud deposits separates layer Cm from the coarse layer Cy at the top of the set. Shovel handle is about 50 cm long. Photograph taken in 1986.