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ABSTRACT

The study of surface samples was used to determine the marsh foraminiferal distributions in five marsh areas in Nova Scotia: Chezzetcook Inlet. Chebogue Harbour, Wallace Basin, Summerville marsh, and Newport Landing.

Detailed surface sampling in Chezzetcook revealed that marsh foraminifera are distributed in well-defined vertical zonations with respect to mean sea level and closely parallel marsh floral zonations. These zones vary slightly between marshes but appear to remain broadly similar throughout the world.

The foraminiferal zonation in Chezzetcook Inlet is used to exemplify the general situation in Nova Scotia. In this estuary the vertical range of the marsh can be divided into two zones, each divisible into two subzones. Zone II, which covers most of the middle and lower marsh, extends from approximately mean sea level (0) to about +75 cm and is characterized by the presence of Cribrononion umbilicatulum, Ammotium salsum, Miliammina fusca and Trochammina inflata. At +75 cm these forms are replaced by Tiphotroca comprimata and Trochammina macrescens which characterize zone I up to +101 cm, where all foraminifera disappear abruptly. The foraminiferal disappearance marks the higher high water level. This distribution can be used to relocate former sea levels in subsurface material to an accuracy of within ±5 cm.

Less detailed sampling of marsh areas in the other four study localities indicated that the same relationships observed in Chezzetcook occur there as well. Examination of detailed data from southern California and less detailed data from other parts of the world suggests that marsh foraminiferal assemblages can be used universally as accurate indicators of former sea levels.

We describe a new species, Thurammina? limnetis n.sp. and, using an intergradational series, we place Jadammina polystoma in synonymy with its senior, subjective synonym Trochammina macrescens.

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