Figure 39. Tephra set Y, Mount St. Helens.

Figure 39A. Multiple coarse beds in layer Yb about 5 km northeast of the volcano. Shovel lies on oxidized top of set J.

Figure 39B. 11 km due east of the volcano. Pick head lies on oxidized top of set J. Layer Yb consists of scattered lapilli and a few bombs in ash overlain by a few centimeters of coarse and fine beds of layer Yd and finer ash of undetermined origin. Layer Yn consists of only about 1 cm of pale-brown ash. Knife is at top of set Y.