Figure F18. Photomicrographs documenting the composition of accessory lithologies in Unit I. Green zeolitic clay layers are shown in (A) plane-polarized light (PPL) and (B) cross-polarized light (XPL) (interval 191-1179B-2H-5, 38.5 cm). Vitric ash layers are shown in (C) PPL and (D) XPL (interval 191-1179B-2H-2, 60 cm).