Gradient - Materials from the Continental Shelf
Gradient_Fragment_II, 1993-2012, a selection from the video, Gradient, 1993. These videos scroll a partial listing of minerals, elements and rock-types theoretically inherent in the sediment shown here collected, and encapsulated within the public sculpture, Deep Gradient/Suspect Terrain.., 1993 - johnroloff.com/yerbabuena_ship_page.html -. The materials being shoveled in the video are
sediments collected from the Pacific Ocean sea floor several miles off the coast of central California. The sediments were collected with the help of Tim Collins using a dredge operated from the fishing boat, Pearl, out of Oakland, CA. This assemblage of materials is representative of the eroded and transported geology underlying the watershed that includes the Sacramento, Feather, Napa, Cosumnes, Mokelumne, American, San Joaquin and Merced Rivers. This system empties out through the Golden Gate, and gathers sediment from a landscape that ranges over most of the length of the Great Valley, the central and eastern slopes of the Sierra Nevada and much of the Coast Ranges of Central California. Video by Ann Wettrich/John Roloff
