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Three layers of sand occur within a sequence of muddy gyttja in a 3 m core recovered from Deserted Lake, which lies at the head of a fjord on the central west coast of Vancouver Island, British Columbia, Canada. The sedimentology and microfossil assemblages of these layers are consistent with deposition by tsunamis. Radiocarbon ages suggest that the tsunamis were generated by plate-boundary earthquakes at the Cascadia subduction zone about 2600, 1600 and 300 years ago. Diatom and protozoan contents of the gyttja layers indicate that relative sea level fell in the periods between tsunamis. The sea-level changes are probably a product of interseismic uplift of the North America plate margin. Post-tsunami diatom and protozoan assemblages are generally more marine than their pre-tsunami counterparts, suggesting that the study site subsided during earthquakes. Estimates of interseismic and coseismic deformation during one earthquake cycle indicate that less than half of the interseismic uplift was recovered during the earthquake, leading to cumulative, or permanent, uplift of the area.

A large integrated data set of cores, outcrop data, and seismic transects from the mud-buried Vars-Winchester esker in the Champlain Sea basin, Canada, was studied to gain insight into how muddy glaciated basins fi ll with sediment, and how esker sedimentary systems contribute to this process.Three stratigraphic units-a till sheet over carbonate bedrock, the Vars-Winchester esker , and overlying Champlain Sea mudare identifi ed in the data set. The till is massive, mud rich, carbonate rich, and drumlinized. The esker is also carbonate rich, and rests erosively on till or bedrock. It consists of two elements, a narrow gravelly central ridge and a broad sandy carapace. Three units comprise the overlying mud package: gray carbonate-rich rhythmites, massive bioturbated mud, and carbonate-poor, red-andgray rhythmites. A sequence stratigraphic model is proposed to explain these observations. Emphasis is placed on gradual ice-front translation superimposed by rapid meltwater events. The esker is interpreted to have been derived from the underlying till by water that fl owed through a subglacial conduit (R-channel), within which the narrow gravelly central ridge was deposited. Most mud and fi ner sand bypassed the conduit and was deposited proglacially on the fl oor of the Champlain Sea, fi rst as sandy outwash and, farther basinward, as muddy carbonate-rich rhythmites. Gradual ice-front retreat superposed distal facies over proximal facies, generating the upward-fi ning succession that starts with the esker gravel and ends with muddy rhythmites. Most esker sediment appears to have been deposited during rapid, jökulhlaup-like fl oods that punctuated grad-ual retreat. Discharges are estimated to have been high, possibly on the order of several hundred to, perhaps more commonly, several thousand cubic meters per second. The chaotic and random-looking appearance of the resultant sedimentological signatures in the esker sensu stricto is sharply contrasted with the regularity of the muddy rhythmites. If the rhythmites are indeed correlative to the esker, which seems reasonable given their geochemistry and the fact that their volume scales to the volume of mud in the till, the fl ood events that deposited the esker must have been seasonally mediated, and the basin water must have attenuated the fl ood signal, resulting in a rhythmic "on-off" signature in more distal portions of the system. The regularity of the rhythmites does not betray the chaotic nature of the esker sensu stricto, and vice versa. Studying either one in isolation would lead to a very different "end-member" impression of how eskers form and how esker sedimentary systems operate during the infi lling of glaciated basins.

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