Participants should plan to arrive in Riverside by June 18. We will depart from the University of California, Riverside campus the morning of June 19. We will drive 5 hours to the White-Inyo Mountains. We will spend the remainder of June 19 and most of June 20 visiting the upper Ediacaran through lower Cambrian succession of this area, including a rich assemblage of trace fossils and some of the earliest Laurentian biomineralized fossils. We will drive to Beatty, NV the evening of June 20. On the morning of June 21, we will visit upper Ediacaran strata and an Ediacaran-Cambrian boundary section of the Reed Dolomite and Deep Spring Formation at Mount Dunfee and see Ediacaran microbialites, tubular body fossils and some of the oldest complex trace fossils. We will spend midday at the nearby ghost town of Gold Point, NV, and have an opportunity to see the spectacular early Cambrian archaeocyathan reefs of the Poleta Formation at Stewart’s Mill in the afternoon. We will depart Beatty the morning of June 22 and return to Riverside by way of Death Valley, where we will make brief stops to discuss the stratigraphy of the Death Valley region, Neogene lake deposits near Shoshone and Cryogenian diamictites and the Marinoan cap carbonate exposed in the Saddle Peak Hills and at Sperry Wash. We will be staying in motels in Big Pine, CA (June 19) and Beatty, NV (June 20–21); participant lodging for these days will be covered by field trip fees. Lunches on all four days (June 19–22) and breakfast on the third day of the trip (June 21) will be provided; participants will be responsible for all other meals. We will return to Riverside in the late afternoon on June 22, in time for participants to check in to conference lodging. See Figure 1 for a map of field trip destinations.

Siliciclastic sediments of the Ediacaran Period contain exceptionally preserved fossils of macroscopic organisms, including three-dimensional casts and molds commonly found in sandstones and siltstones and some two-dimensional compressions reported in shales. The sporadic and variable associations of these exceptionally preserved macroscopic fossils with pyrite, clay minerals, and microbial fossils and textures complicate our understanding of fossilization processes. This hinders inferences about the evolutionary histories, tissue types, original morphologies, and lifestyles of the enigmatic Ediacara biota. Here, we investigate the delayed decay of scallop muscles buried in quartz sand or kaolinite for 45 days. This process occurs in the presence of microbial activity in mixed redox environments, but in the absence of thick, sealing microbial mats. Microbial processes that mediate organic decay and release the highest concentrations of silica and Fe(II) into the pore fluids are associated with the most extensive tissue decay. Delayed decay and the preservation of thick muscles in sand are associated with less intense microbial iron reduction and the precipitation of iron oxides and iron sulfides that contain Fe(II) or Fe(III). In contrast, muscles buried in kaolinite are coated only by,10 lm-thick clay veneers composed of kaolinite grains and newly formed K- and Fe(II)-rich aluminosilicate phases. Muscles that undergo delayed decay in kaolinite lose more mass relative to the muscles buried in sand and undergo vertical collapse. These findings show that the composition of minerals that coat or precipitate within the tissues and the vertical dimension of the preserved features can depend on the type of sediment that buries the muscles. Similar processes in the zone of oscillating redox likely facilitated the formation of exceptionally preserved macrofossils in Ediacaran siliciclastic sediments.