Figure F16. The groundmass of the flow-banded sample from Unit 10 consists of domains of completely coalesced microspherulites and domains with isolated microspherulites in altered glass (fine-grained clay and silica) corresponding to the light gray and dark gray bands in hand specimen. The arrow indicates the bulbous outer margin of the devitrified domain (interval 193-1188A-12R-1 [Piece 12, 123-124 cm]; in plane-polarized light; width of view = 5.5 mm. Photomicrograph ID# 1188A

Figure F16. The groundmass of the flow-banded sample from Unit 10 consists of domains of completely coalesced microspherulites and domains with isolated microspherulites in altered glass (fine-grained clay and silica) corresponding to the light gray and dark gray bands in hand specimen. The arrow indicates the bulbous outer margin of the devitrified domain (interval 193-1188A-12R-1 [Piece 12, 123-124 cm]; in plane-polarized light; width of view = 5.5 mm. Photomicrograph ID# 1188A_55; thin section 11).