Frontispiece. A. Close-up photograph of breccia composed of clasts of crystalline basalt intruded by fingers of black glassy basalt and cemented by a hydrothermal assemblage of amphibole, chlorite, and chalcedonic quartz (white) (interval 206-1256D-26R-2, 14–32 cm). B. Photomicrograph of prismatic green to brownish green amphibole in breccia intruded by altered glassy finger of basalt (Sample 206-1256D-26R-2, 22–25 cm) (field of view = 1.25 mm; plane polarized light). C. Close-up photograph of basalt highly altered to low-temperature hydrothermal assemblage of celadonite, silica, iron oxyhydroxide, and secondary feldspar (interval 206-1256D-57R-3, 0–17 cm). D. Close-up photograph of hyaloclastite breccia containing clasts of fresh brownish glass and of microcrystalline basalt (light gray at 0–5 and 11–13 cm). The rims of clasts of brownish fresh glass are altered to and cemented by a dark phyllosilicate (possibly saponite) (interval 206-1256D-30R-1, 0–14 cm). E. Photomicrograph of hyaloclastite showing fresh (pale brown) and altered (dark brown) glass. Fresh glass shards are surrounded by a rim of glass altered to clay minerals (Sample 206-1256D-20R-1, 27–29 cm (field of view = 10 mm; plane polarized light).