Figure F29. Photomicrograph of Sample 183-1137A-45R-2 (Piece 1A, 7-10 cm) from the breccia at the top of basement Unit 10 showing in situ brecciation of glassy volcanic clasts forming jigsaw-fit textures. Penetrative brecciation could be caused by the dynamic injection of fluidized sediment or a combination of subaerial cooling and mechanical grinding. Field of view = 5.50 mm (plane-polarized light).