1. Obsidian Terrace (Seabird Caves) / Shell Mound (White Forest), Proposal for Double Rock, San Francisco, CA Bookmark Obsidian Terrace (Seabird Caves) / Shell Mound (White Forest), Proposal for Double Rock, San Francisco, CA, accession number 2020.27.22. Search result 1 Artist: Roloff, John Classification: Mixed media Materials: pencil, ink and acrylic on black and white photo Dimensions: 40 x 72 in. Accession Number: 2020.27.22