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The evolution of submarine canyons is primarily controlled by turbidity currents, which erode and fill them over time; however, many other hydrodynamic currents operate within canyons. Bottom currents from these other hydrodynamic processes, including internal tides, can be dominant processes, but their deposits are seldom recognized in sediment cores or the rock record. This study combines autonomous underwater vehicle swath bathymetry imagery and sub‐bottom profiles, high‐resolution sediment core analyses (X‐ray imagery and thin sections), and previously collected seabed video and flow measurements within Logan Canyon head (eastern Canada) to provide a detailed, modern record of facies associated with hydrodynamic processes in a canyon head. These results suggest that bottom currents are responsible for maintaining gullies on canyon sidewalls and an axial channel on the canyon floor. Thin sections of sediment cores reveal that muddy sand in the canyon head consists of mud aggregates and silt and fine‐grained sand, both behaving similarly in terms of flow dynamics. Three facies are present at macro‐scale and micro‐scale: laminated, partially laminated and bioturbated sandy mud. Sedimentary structures include rhythmic sand and mud aggregate couplets, planar to wavy laminations, current ripple cross‐laminations and fining‐upward successions, which are attributed to bottom currents induced by internal tides. Bioturbated facies, characterized by discrete biogenic structures and cross‐cutting relationships, predominate and overprint a mottled background. A mottled bioturbation fabric also alternates with or locally disrupts layering within the partially laminated facies. Internal tide currents, capable of bedload transport and forming ripples, were measured during a monitoring period in the canyon head, followed by rapid re‐establishment of benthos and associated biogenic structures, supporting the core interpretations. Preservation of sedimentary facies associated with these internal tides occurs when the sedimentation rate outpaces the rate of bioturbation, likely during stormier conditions on the shelf. These results represent observations of sedimentary facies associated with modern bottom currents and internal tides, and can be used to interpret similar occurrences within the rock record. [ABSTRACT FROM AUTHOR]

Rotationally‐modified gravity currents are known to occur on the ocean bottom in many locations around the world. Although their time scales are long enough that the Coriolis force is important in their dynamics, tidal forcing may also play a role in intermediate‐term variability by periodically enhancing or diminishing the flow and bottom friction, although the importance and implications of this variability has not previously been studied. Here we investigate hourly‐to‐tidal variations in the turbidity and density of intermittent gravity currents associated with deep‐water renewal events in the Strait of Georgia, Canada. We find that features such as the height and magnitude of the gravity current's nose, as well as bottom stress, undergo tidal variations, and that sediment resuspension largely occurs at the times of greatest stress at peak flood, with highest turbidities occurring in the hours following that peak. Larger particles soon settle again, but smaller ones can remain suspended. In addition, there is a significant tidally‐driven lateral advection of the gravity current, which results in density fluctuations in observations at a fixed location. Plain Language Summary: The ocean bottom is not flat, and in many cases heavy water moves from one ocean basin to another by flowing over sills and downhill into the next basin. These "gravity currents" are affected by both the earth's rotation, causing them to turn rightwards (in the northern hemisphere) into the slope, and by tidal currents in the ocean above. Here we find that tides speed up and slow down a gravity current in the Strait of Georgia, Canada, and that in turn means that the current can pick up particles off the bottom only at certain times in the tidal cycle when currents at the bottom are strongest. The tides also move the gravity current sideways, which makes it difficult to separate out the effects of tides within the current and their effect on the location of the current. Key Points: A rotationally‐modified gravity current in the Strait of Georgia, Canada, has strong tidal variations in its vertical structureSignificant sediment resuspension occurs at and just after the peak flood tides when tidal flow is added to the gravity currentThere is also a significant lateral advection of the current, associated with large‐scale tidal currents [ABSTRACT FROM AUTHOR]