• Debris-dominated foreslope. Shallow organisms reworked in open basin environment as centimetric breccia; matrix indicates a deep environment with radiolarians

• These outcrops are part of the Eastern Klamath terrane, a sequence of Palaeozoic and Mesozoic island arc deposits that were built upon oceanic crust (Irwin 1977) and accreted onto the American continental margin during the Mesozoic (Coney et al. 1980). It is worth to notice that the best-preserved limestone units crop out in the Shasta Lake area and not at the type locality (Taylorsville, Plumas County). In the Shasta area, the lower part of the Hosselkus Limestone shows a great variety of open basin facies (e.g., deep environment with radiolarians, condensed levels of halobid-like bivalves, crinoids packstone, calciturbidites with ammonoids). After a progressive transition toward shallower basinal facies, the whole succession is covered by several meters of breccia composed of centimetric to decimetric limestone clasts within a radiolarian-rich fine matrix. The limestone clasts derive from an Upper Triassic carbonate platform that no longer exists. Facies mostly reflect platform top to foreslope environments, with mud-dominated and grain-dominated elements associated with shallow-water organisms; the last are observed in millimetric to decametric reworked elements, and notably comprise the here described algae and coral-rich facies. Conodonts recovered in all three types of facies indicate a late Carnian age