A paleomagnetic and magnetic anisotropy study of the Late Cretaceous Northumberland formation on Hornby Island, British Columbia, was conducted to determine if burial compaction could have caused its anomalously shallow inclinations. The shallow Nanaimo Group inclinations have been used to support the Baja British Columbia (Baja BC) model of continental dynamics in which superterranes were transported thousands of kilometers northward along the active North American continental margin in the Cretaceous. A mean of the site means from the Northumberland formation is D = 5.8°, I = 50.9°, α95 = 7.9° (N = 8). Anisotropy of magnetic susceptibility (AMS) and anisotropy of anhysteretic remanence (AAR) were measured to identify and correct for any inclination shallowing caused by depositional/compactional processes. Both concretion and fine‐grained rock samples had typical depositional/compactional AMS and AAR fabrics with bedding perpendicular minimum principal axes. A revised correction equation was used to account for the effects of either triaxial magnetic fabrics or small angular deviations of principal axes from the bedding plane. The average inclination was increased by 9.6° after the compaction correction (D = 6.1°, I = 60.5°, α95 = 7.1°, N = 8), and the mean inclination of concretion and fine‐grained rock sites was significantly steeper than Ward et al.'s [1997] result (I = 42.5°) placing Hornby Island and the Insular superterrane at a paleolatitude of 41°N in the Late Cretaceous. This paleolatitude indicates that Baja BC did translate northward since the Late Cretaceous by about 1600 km but not by the 3500 km previously indicated.

S U M M A R YEnvironmental magnetic studies of annually laminated sediments from Lake Ely, northeastern Pennsylvania, USA indicate that bacterial magnetite is the dominant magnetic mineral in the lake sediment. In previous studies of Lake Ely sediment, the dark, organic-rich layers in the annual laminae were interpreted to have high-intensity saturation isothermal remanent magnetizations (SIRMs) while the light-coloured, silt-rich layers have low-intensity SIRMs.To test the hypothesis that the magnetic grains in the sediments were an authigenic product of magnetotactic bacteria rather than detrital magnetic grains eroded from the watershed, we analysed samples from the water column, the lake sediment, and a sediment trap installed near the lake bottom. Direct microscopic observation of the water column samples showed the presence of magnetotactic bacteria in and below the oxic-anoxic transition zone (OATZ). To characterize the magnetic minerals, rock magnetic parameters were measured for material from the water column, the sediment trap and the dark-and light-coloured lake sediments. Lowtemperature magnetic measurements tested for the presence of magnetosomes in separated dark-and light-coloured layer samples. Numeric unmixing of the low-temperature results showed that biogenic magnetites were present in the lake sediment and contributed more significantly to the SIRM in the dark, organic-rich layers than in the light-coloured, inorganic silt-rich layers. Observations under the transmission electron microscope (TEM) of magnetic extracts also show the abundance of magnetosomes in the lake sediment. The presence of live magnetotactic bacteria in the water column and the predominance of bacterial magnetites in filtered particulate matter, sediment traps and recent lake sediment all suggest that bacterial magnetites are the main magnetic minerals in Lake Ely sediment. This finding suggests that changes in environmental factors that control the productivity of magnetic bacteria in the lake likely contribute to the variability of magnetic mineral concentrations observed in the lake sediments.