Previous studies have interpreted the Paleoproterozoic Reany Creek Formation as a glacial deposit based largely on the presence of lonestones that were regarded as dropstones. In the first paper of this three-part series (Larue, 2026b), a new classification system was introduced to more precisely describe and interpret lonestones. That framework is applied here to the Reany Creek Formation, in which five distinct lonestone types are recognized. Type 1 lonestones are outsized clasts resting in and disrupting layering within laminated mudstone. Type 2 lonestones occur within homogeneous mudstone beds. Type 3 lonestones form chains of outsized clasts in mudstone intervals, sometimes showing a basal erosional contact. Type 4 lonestones are isolated clasts immediately above pebbly mudstone units in laminated muddy sediments. Type 5 lonestones are outsized clasts residing in tectonically foliated mudstone. The findings of this study indicate that none of these lonestone types can be uniquely attributed to glacial dropstone origins. Lonestone types 2 through 5, and possibly type 1, have also been documented within non-glacial, deep-water deposits of the Cretaceous Pigeon Point Formation and the Miocene San Onofre Breccia in California. The Reany Creek Formation consists predominantly of mudstone interbedded with abundant conglomeratic intervals and subordinate sandstone beds. All conglomerate and sandstone units are interpreted as products of sediment gravity flows, while the mudstone intervals record hemipelagic settling and low-density turbidity currents. Soft-sediment deformation structures are common within the muddy facies, indicating syndepositional instability. Lonestone types 2, 3, and 5 are interpreted as components of sediment gravity-flow deposits. The overall stratigraphic architecture and associated sedimentary features are consistent with deposition in a deep-water slope environment. This interpretation is supported by close sedimentological parallels with the non-glacial Pigeon Point Formation, which provides a modern analogue. Importantly, no sedimentological or stratigraphic evidence was found to support glacial influence during deposition of the Reany Creek Formation.
D.K. Larue (Fri,) studied this question.