The Holocene sedimentary environment of Cambridge Fiord in northeastern Baffin Island is interpreted from six piston cores. Distinct sediment types represent three sedimentary processes. (1) Muds deposited from suspension from fluvial sources at the fiord head and glacial sources near the mouth are the dominant components of the sediments. The rate of accumulation in mid-fiord based on a radiocarbon date on dispersed organic material indicates an average rate of sedimentation of 1.24 mm/a since about 5800 BP. Upper portions of the cores are bioturbated, although bands of well-preserved fine rhythmites indicate the sudden loss of the benthos, perhaps caused by oxygen depletion associated with reduced circulation. Rhythmites near the sediment surface have a mean thickness similar to the calculated annual accumulation, indicating that they probably are varves; those at depth average 8.1 mm thick. Fine sediment at depth in several cores was not bioturbated for long periods, indicating reduced effectiveness of the benthos during periods of higher rates of sedimentation. Graded muds and sandy muds are interpreted as deposits from weak underflows generated in the sediments on the fiord walls. (2) Massive sands deposited near the head of the fiord are the result of cohesionless debris flows from sources of fluvial and littoral sand widely distributed along the fiord floor. (3) Single sand- and pebble-sized particles found everywhere in the muds are interpreted as ice-rafted debris.

Locomotion and feeding traces (repichnia and fodichnia) observed on bedding planes of rhythmically bedded subaqueous outwash deposits in the Brazeau sand pit, Nepean, Ontario, Canada, are the first bedding-plane traces described in detail from the western Champlain Sea. The Planolites–Palaeophycus-like and Taenidium-like traces are cylindrical with circular cross section, smooth sided, unlined, sinuous, sometimes branching, and sometimes meniscate. Organisms producing the traces are tentatively identified as errant polychaetes or nemerteans. The enclosing sediments are rhythmic couplets of alternating fine sand and silt layers overlain by silty clay and fine–medium silt layers. The occurrence of traces within the uppermost portion of the coarse unit, and within the coarser, upper portion of the overlying fine unit, and the rhythmic alternation of coarse and fine layers suggest these deposits may be varves. The traces formed during the more biologically suitable summer months but were preserved only during the latter portion of the summer. Traces are distributed on bedding planes in close association with bedforms and show a high correlation with the substrate and possibly the hydrodynamic regime. This is interpreted as indicating a strong preference in feeding behaviour. The presence of traces in the subaqueous outwash environment necessitates rethinking of the depositional environment to include the presence of errant polychaetes, nemerteans or similar organisms, and the lower life-forms such as epontic algae and bacteria on which they live.

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The Foster sand pit exposes pre- to late-Champlain Sea sediments containing 4 litho/biofacies. These are, from oldest to youngest: Faciès 1- cross-stratified sand and diamicton deposited as late-glacial, ice-proximal subaqueous outwash. Faciès 2- laminated silt and clay rhythmites with a sparse Candona cf. C. subtriangulata ostracode fauna deposited in a deep, proglacial lake preceding the Champlain Sea, Fades 3- massive to rarely laminated silty clay with dominant foraminifera Elphidium bartletti, Protelphidium orbiculare and Cassidulina crassa represents the first glaciomarine deposition in Champlain Sea water 30-100 m deep with a paleosalinity of 22-33 %o. Faciès 4- mixed bedding of sand and mud, with a microfossil assemblage dominated by the Elphidium/Protelphidium complex representing an intertidal offlap sequence. Water depths during deposition of Faciès 4 dropped to 10-30 m. and paleosalinity dropped to 18-28 %o.. This study recognizes a pre-Champlain Sea proglacial lake, assigns subaqueous outwash deposits to an earlier time than previously believed and documents changes in bottom water characteristics of the early Champlain Sea based on sedimentary and microfossil evidence.La sablière Foster laisse voir des sédiments glacio-lacustres et du début de la Mer de Champlain qui comprennent quatre litho-biofaciès. Les faciès, du plus vieux au plus récent, sont les suivants: Le faciès n° 1 est composé de sable et d'un diamicton à stratification oblique qui se présente comme un épandage fluvio-glaciaire subaquatique tardiglaciaire. Le faciès n° 2 est composé de silt laminé et de rythmites d'argile comprenant une faune peu abondante d'ostracodes {Candona cf. C. subtriangulata): ce faciès a été mis en place dans un lac proglaciaire profond qui a précédé la Mer de Champlain. Le faciès n° 3 est une argile silteuse d'aspect généralement massif avec quelques rares lamines renfermant les foraminifères Elphidium bartletti, Protelphidium orbiculare et Cassidulina crassa; ce faciès représente le premier dépôt de la Mer de Champlain mis en place à 30-100 m de profondeur; la paléosalinité était de 22-33 %o. Le faciès n° 4 formé de lits de sable et de boue mélangés, comprend un assemblage de microfossiles dominé par le complexe Elphidium - Protelphidium, qui représente une séquence intertidale de régression. Au cours de sa mise en place, la profondeur d'eau s'est abaissée jusqu'à 10-30 m, et les eaux se sont progressivement dessalées jusqu'à 18-28 %o. Dans cette étude, on reconnaît l'existence d'un lac proglaciaire précédant la Mer de Champlain. on attribue aux dépôts d'épandage subaquatique un âge supérieur à ce que l'on croyait auparavant et on fournit des renseignements sur le caractère changeant des eaux plus profondes du début de la Mer de Champlain fondés sur des preuves découlant de l'étude des sédiments et des microfossiles

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