Abstract A study of well constrained, modern lake sediment oscillations in Loon Lake and Aylesford Lake, Nova Scotia was undertaken with the intent of understanding the processes that influence clastic sedimentation and sediment mobility in small, shallow, dystrophic organic lakes. The sediment oscillation in Loon Lake is characterised by an increase in the clay content, a decrease in L.O.I. and a sharp lower contact with the underlying gyttja. The sediment oscillation at Aylesford Lake is produced by managed lake level drawdown and the transfer of littoral sediment to the profundal zone by ice-rafting processes. This horizon has gradational boundaries and the overlying gyttja is characterised by increased clastic content. The intra-basin distribution of the oscillation is highly dependent on water depth and wind direction at the time of disturbance.
Oscillations produced by lake level fluctuations tend to be coarser grained and more diffuse.
Significant volumes of gyttja can be transferred basinwards during the drawdown event. A laboratory study of the interaction between free-falling clastic sediment and gyttja indicated that the introduced sediment will settle through the gyttja, consequently coarse oscillations have the potential to be significantly younger than the bounding gyttja. These studies indicate that the physical characteristics of oscillations are highly dependent on the mode of formation. As well, significant sediment oscillations can be produced by very short-term events and do not necessarily need to be a product of a sustained environmental change.