Figure F24. Close-up photograph of interval 183-1139A-60R-2, 54-61 cm, showing the dark red highly altered, rhyolite breccia at the base of basement Unit 4. The breccia has an open framework texture and is not welded. This differs from the welded material observed at the top of basement Unit 4. Red clasts have thin (<2 mm), light green alteration rims and are set in a red clay-rich matrix. Some fresh phenocrysts are present.