Robert Smithson, Cambrian Map of Sulfur and Tar, 1969.jpg

Robert Smithson, "Cambrian Map of Sulfur and Tar," 1969. Crayon and marking pen on paper, 17 × 14 in. The Menil Collection, Houston, Gift of the artist. © Holt / Smithson Foundation / VAGA at Artists Rights Society, NY. Photo: Paul Hester. Courtesy MDI.