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The Mackenzie Trough provides a high resolution signal for paleoceanography as a result of high sedimentation rates at the mouth of the Mackenzie River. Three cores were collected along a transect covering a depth range of 58–671 m and the time period of the last 11 500 cal BP. Prior to the last ∼10 000 cal BP, the distal core is characterized by laminated sediment and a foraminiferal fauna of Arctic Bottom Water calcareous species and abundant planktic foraminifera suggesting little freshwater runoff and (or) perennial sea-ice cover. This occurs at a similar time as laminated sediments from the west of this site, which have been suggested to be part of the Lake Agassiz flood outburst and (or) cold period. If this outburst occurred, the very positive oxygen isotope values from our core (PC3; >+3.0 ppm) indicate that it did not flow through the Mackenzie Trough. After 9000 cal BP, the faunas in the three cores differ because of timing and different water depths. However, it is possible to see a progression of cold saline water prior to 10 000 cal BP, with a freshening of surface water after 10 000 cal BP where tintinnids (brackish water ciliates) occur with incursions of deep water Arctic calcareous species to ∼3000 years BP. A sequence of mixed faunas appears as sea ice returns, at least periodically in the last 3000 cal BP; but (in core PC2 only) a return to more sea ice is recorded by both foraminifera and dinocysts in the last few hundred years.

Two vibracores collected from Halifax Harbour allow reevaluation of the early postglacial history and part of a new sea-level curve for eastern Nova Scotia. An acoustically distinct seismic unit found throughout Halifax Harbour, but never previously sampled, occurs in the base of one core. Analysis of foraminiferal assemblages within this unit suggests estuarine conditions, not lacustrine as previously suggested. An in situ peat sample from the second core yields a date of 7770 ± 260 BP, and, based on the marsh foraminifera present, provides a sea-level point at -26.1 m. The foraminifera from the estuarine deposit yielded a date of 8480 ± 60 BP. The estuarine sediments are reddish, have a low organic content, and are very different from present-day estuarine sediments in this area, providing us a rare glimpse at early postglacial estuarine environments. This estuarine deposit represents deeper water than does the peat and indicates that sea level was higher prior to 7770 BP. Earlier papers suggested that sea level had been higher before 7000 BP, but the points presented here are the first data from this interval providing both spatial and temporal control on this critical interval of sea-level history. The new sea-level curve presented in this study, together with another recently published curve, shows two periods of emergence, one prior to 11 000 BP and another between 8000 and 7000 BP. The earlier emergence was probably the initial elastic rebound following ice removal; the second one may be the passage of the glacial forebulge predicted by theoretical models.

Assemblages of foraminifera and Arcellacea examined from surficial sediment samples collected in Porters Lake, Nova Scotia, reflect the strong gradient from freshwater to marine water in the four basins of this lake. The only marine connection is a channel 3 m below higher high water. The transition from fully freshwater to marine is abrupt, with no "intermediate" arcellacean fauna, as we have observed in cores from other areas of the Maritimes, Given the present connection is 3 m below higher high water, it has been almost 1500 years since this sill first became tidal (based on 20 cm/100 year sea-level rise from nearby Chezzetcook Met over the last 3000 years); however, the upper fjord-like part of Porters Lake, although connected to the ocean, is still completely freshwater, suggesting at least a 1500 year time lag for marine conditions to penetrate upper reaches of the lake. For the first time, we are provided with a time frame of how long it takes for marine conditions to extend into remote parts of an estuary, which could have implications for interpreting records from other similar fjord-type estuaries, such as Bedford Basin, Nova Scotia. Evolution of the lake through time was studied from three cores: one from the present most marine conditions, one from an intermediate area, and one from the uppermost freshwater part of the lake. Porters Lake has experienced marine transgression for at least the last 3000 years, with one closure between 1500 and 2000 BP. Bottoniset beds from a glaciogenic gravel delta at the head of the lake were dated at 11 750 BP; this is similar to an age on a delta offshore that is now in 70 m of water.

A new late Holocene sea-level curve is presented from the Atlantic coast of Nova Scotia. Contrary to earlier data from the same area, this curve starts at 4400 sidereal years before present (BP) and shows a rapid acceleration between 4400 and 3800 BP, which coincides with a similar acceleration already reported from the Northumberland Strait (Nova Scotia) and an oscillation observed in South Carolina. Comparing the two Nova Scotia curves suggests that the acceleration lasts just over 1000 years and has a vertical extent of 10 m. One puzzling fact is that the 10 m vertical extent in Nova Scotia is 8 m more than the same event measured in South Carolina and it cannot be accounted for simply by postglacial isostatic depression, since that occurs on a much longer time scale. A closer examination of most of the sea-level curves from northeastern North America reveals that either the record is missing from this interval or it is inconsistent. We suggest that this acceleration is part of a global response that coincides with the end of the mid-Holocene warming period, possibly indicating a lag response between warming and ice melt.

The sedimentary sequence in a coastal pond on Cape Breton Island was examined by various analyses (pollen, plant macrofossils, diatoms, and rhizopods). The results allow for the reconstruction of different phases in the evolution of the pond in conjunction with relative sea-level rise during the late Holocene. Throughout the period studied the microflora and microfauna indicate that the pond was mainly freshwater, isolated from the sea by a continuous sand and gravel bar. Three phases in the pond evolution have been identified: (1) the lowermost part of the sequence is characterized by mineral detrital deposits and some marine fossils related to the reworking of bar sediment by storms and high tides washing over the rock sill; (2) this was followed by a rapid filling of the basin by organic detritus provided by shore washing processes; (3) a marsh evolving into a shallow lake completes the sequence up to the interruption by human occupation. The lake-level rise is linked to the formation of the bar, which was controlled by the highest storm-beach level. A submersion rate of 18 cm/century has been calculated using the beginning of the lacustrine phase, which was dated at 2680 years BP (UQ-616).

Three piston cores from Bedford Basin, a silled coastal inlet, provide the basis for a micropaleontological study of postglacial to recent sediments. Five faunal units (four foraminiferal, one arcellacean) are found in core 79-11: a surface assemblage, followed by deep estuarine, marginal marine, transition, and freshwater (arcellacean) assemblages. The other cores contain only expanded marine sequences. The top of the transition zone in core 79-11 has a C-14 age of 5830 ± 230 years BP, indicating a rise in sea level of at least 20 m (the sill depth) during the Holocene.Four dinoflagellate assemblage zones are found in core 79-11. The first (O. centrocarpum – B. tepikiense) is typical of a silled basin with marine water of near-normal salinity; the second (P. conicoides – Cyst C) indicates a temperate marine environment with strong fluvial influence (marginal marine); the third (P. limbatum) is dominated by freshwater cysts, and the fourth (Dinocyst sp. A) is dominated by subarctic brackish water cysts.Four pollen assemblage zones are found in core 79-11. Zones C1–C3 indicate mixed boreal–deciduous forest vegetation. Zone B indicates early Holocene park–woodland vegetation, the base of which has a C-14 age of 7705 ± 550 BP. The palynozones in the marine sediment core are correlatable with C-14 dated stratigraphies from Nova Scotian lakes.Foraminifera and dinoflagellate assemblages in core 79-11 reflect the response of the microfauna and microflora to changes in water depth, salinity, and temperature, which have accompanied changes in sea level and climate during the past 8000 years. Major changes in the marine biota during the recent period of urban development may be due to increased sediment influx and effluent discharge. The effects of anthropogenic changes are small, however, compared to those accompanying the Holocene marine transgression.

Previous studies of sea-level and tidal amplification in the Bay of Fundy suggested a linear increase of tidal amplitude as relative sea level rose. New data presented here are used in a numerical tidal model in an effort to reproduce paleotidal regimes over the last 7000 years. Five new sea-level curves covering the last 4000 years and some previously published data extending the record back to 7000 years before present (BP) are used as the data base. These data, when used together with the tidal model, indicate that tidal amplitudes increased much more rapidly between 7000 and 4000 years ago than in the period 4000 years ago to present. It is also shown that changes in depth within the Bay of Fundy produce little effect on the tidal amplitudes, whereas such variations in water depth on Georges Bank account for almost all the change. This calculation of tidal-amplitude changes allows calibration of sea-level curves to be made for the Bay of Fundy using higher high-water (HHW) indicators.

Distribution of foraminifera from surface sediments collected during September 1975 and February 1976 in Miramichi estuary are described and compared to similar data reported previously from the same estuary. Three major assemblage zones presently occupy the estuary: the river, transitional, and open bay assemblage zones. Only two assemblage zones were observed in earlier studies: river and open bay. Sedimentological and geomorphological evidence suggests that circulation patterns in the estuary have changed sufficiently in the past decade to allow the transition assemblage to replace the open bay in large parts of the estuary.A comparison is made between the distributions obtained using a cluster analysis and those obtained using a direct, intuitive approach. The two methods yield almost identical results in this study and the cluster analysis should be a valuable tool when large amounts of data must be interpreted.Seasonal observations were limited; however, no major shifts of faunal zones were detected from September to February. One species, Protelphidium orbiculare, appears to be more common in the warmer months and may require relatively warm temperatures to reproduce.A new complementary classification of estuaries based on circulation detected by foraminiferal assemblages is proposed.

Sable Island is a 38 km long feature that is situated near the outer margin of the Scotian Shelf between George's Bank and the Laurentian Channel. Grab samples of the predominantly sandy substrate that surrounds the island's offshore areas were collected from water depths of 0 to ~55 m.Textural data indicate that winnowing processes are comparatively intense in offshore areas, especially on the north side of the island. A higher frequency of samples containing more than 2% clay-size particles occurs in an area lying off the southeastern coast of the island. The clay suggests that a pre-Recent source of fines is there or that wave energy conditions are somewhat reduced at this locality.Cluster analysis of foraminiferal percentage data defines several foraminiferal thanatotopes. The largest one is dominated by Eggerella advena, with large percentages of Elphidium and Trochammina. The second largest thanatotope is distinguished by its comparatively high porportion of miliolid species and by the highest mean percentage of E. advena.The offshore shelf environment around Sable Island appears to represent an area where several regional assemblage zones overlap. The factors controlling local assemblage distribution patterns in the shelf environment surrounding the island do not appear to be related directly to ambient water-mass characteristics. However, the occurrences of assemblages that include a large proportion of the lower estuarine – nearshore species E. advena may indicate the existence of an influx of groundwater from the island's aquifers to the surficial layer of offshore sediments.Foraminiferal barren zones are apparently related to resuspension and transport of tests to zones of reduced wave energy and to long-term effects of abrasion on the total indigenous thanatocoenoses.

Work on new cores from old core sites in Baie Verte, New Brunswick, led to the identification of submerged salt-marsh peats, reported earlier as freshwater ones. A comprehensive sea-level curve, between 9 and 15 m below present, is based on marsh foraminiferal assemblages. These data indicate that between 4500 and 5400 BP relative sea-level (RSL) rise was comparatively slow (about 10 cm/100 years); the rate increased dramatically between 4500 and 4000 BP (1 m/100 years) and decreased between 2000 and 4000 BP to its present rate of 15 cm/100 years. We suggest RSL was falling before 5400 BP and that the sequence in our deepest core is similar to some observed in the Bay of Fundy and Nova Scotian Atlantic coast where early RSL fall is documented. To account for this sea-level record and others nearby we suggest that the ice history here is complex, with three separate ice caps thinning towards this area in late glacial times.Earlier work also indicated a number of sediment sequences barren of benthonic foraminifera, suggesting a complex marine–freshwater history for the area. The study of new cores containing the same sequences indicates no barren zones but a simple transgressive sequence with a warm-water calcareous fauna followed by an agglutinated transitional estuarine foraminiferal fauna.