The Hunters Cove Formation is a 300-m thick, fining-upward sequence deposited above and perhaps also contemporaneously with Cape Sebastian Sandstone, a transgressive shelf sequence. Overall, the formation is fine-grained (sand:shale < 1:3) and consists of thin, T(a)bc(de) turbidites, siltstone, and shale. Distinctive, thick sandstone beds exhibit varied sedimentary structures indicative of rapid sedimentation, soft-sediment deformation, and fluid-escape processes. These sandstones were probably deposited at a break-in-slope or canyon mouth, resulting in unstable-grain-framework sands susceptible to hydroplastic deformation, liquefaction, and fluidization.
The Hunters Cove Formation also contains small-scale slump zones and a thick slump breccia containing clasts of basal Cape Sebastian Sandstone, indicating that Hunters Cove deposition was contemporaneous with, and may have been initiated by, active faulting. This faulting is also suggested by small-scale penecontemporaneous faults and sheet and web structures. Hunters Cove deposition probably occurred on the edge of a small, fault-bounded, borderland-type basin. In particular, submarine-canyon and fan processes in the California Borderland, as described by Shepard, Dill, and others, may be modern analogies for it.
