Figure F39. Alternating light gray bands of aligned and coalesced spherulites and brown to dark gray bands with only isolated spherulites can be observed in thin sections of flow banded clasts in Unit 25. The banding was generated during high-temperature devitrification, and the dark bands are inferred to represent former volcanic glass between the devitrified, spherulitic bands (Sample 193-1189B-15R-1 [Piece 15, 131-134 cm] in plane-polarized light; width of view = 5.5 mm. Photomicrograph ID# 1189B

Figure F39. Alternating light gray bands of aligned and coalesced spherulites and brown to dark gray bands with only isolated spherulites can be observed in thin sections of flow banded clasts in Unit 25. The banding was generated during high-temperature devitrification, and the dark bands are inferred to represent former volcanic glass between the devitrified, spherulitic bands (Sample 193-1189B-15R-1 [Piece 15, 131-134 cm] in plane-polarized light; width of view = 5.5 mm. Photomicrograph ID# 1189B_42; thin section 133).