Figure F12. Digital photomicrograph (crossed nicols) of a sandy siltstone containing detrital grains of plagioclase, hornblende, biotite, and fragments of planktonic and benthic foraminifers. Rare subrounded grains of basalt with plagioclase and rare hornblende phenocrysts (interval 180-1115C-23R-1, 93-94 cm).