Cars drive on O'Shaugnessy Boulevard past rock formations known as radiolarian chert in San Francisco, Calif. On Friday, June 19, 2015.
Rock formations known as radiolarian chert is seen above a section of O'Shaugnessy Boulevard in San Francisco, Calif. On Friday, June 19, 2015.
Cars drive on O'Shaugnessy Boulevard past rock formations known as radiolarian chert in San Francisco, Calif. On Friday, June 19, 2015.
Rock formations known as radiolarian chert is seen above a section of O'Shaugnessy Boulevard in San Francisco, Calif. On Friday, June 19, 2015.
Cars drive on O'Shaugnessy Boulevard past rock formations known as radiolarian chert in San Francisco, Calif. On Friday, June 19, 2015.
old chromolithograph illustration of life in the oceans, marine animals - 放射蟲類 個照片及圖片檔插圖, 雕刻圖像, 19世紀風格