Figure F22. Photomicrograph of Sample 183-1137A-33R-3 (Piece 1B, 50-53 cm) showing typical internal texture of crystal-lithic volcanic sandstone and siltstone in basement Unit 5. Despite the sharp contact between the two intervals, their content is similar: both siltstone and sandstone contain abundant angular feldspar crystals and crystal-lithic volcanic fragments throughout. Field of view = 2.75 mm (plane-polarized light).