Abstract

Sedimentation occurs in 4 environments in the Bay of Fundy intertidal zone. These environments are (1) wave-cut benches, (2) estuarine clay flats, (3) tidal flats in lee of bedrock islands, and (4) salt marshes. Thin sediment veneers deposited on a wave-cut bench comprise 75 percent of the intertidal zone sediments of the Bay of Fundy. Such sediments are characterized by texture and composition which is similar to that of the underlying bedrock from which it was derived. Wave action and braided streams rework the sediments and leave the following combination of primary structures: lenticular cross-stratification; flutes; grooves; flat-topped, scoured, current, oscillation and interference ripple marks; current lineation; megaripples, and scour pits on the lee side of pebbles. Estuarine clay flats are underlain by unstratified silt and clay which is drained by meandering creeks. Tidal marsh sediments consist of a silt and clay bank overlain by a thin zone of decayed plant debris. Tidal flats in the lee of bedrock islands were subdivided into a higher tidal flat characterized by gravel and sand, and a lower tidal flat characterized by gravel, sand, silt and clay. The higher tidal flats are drained by braided streams. Meandering creeks drain the lower tidal flats and develop a lag concentrate of gravel, sand, and clam shells at the channel bottoms by the process of lateral sedimentation. Comparison of Bay of Fundy intertidal zone sediments and Triassic redbeds of the Canadian Maritime Provinces showed that both are characterized by the same color, texture, and mineral composition because the modern sediments were derived from Triassic bedrock. However, the Triassic redbeds are of different origin as their characteristic combinations of primary structures suggests fluvial and lacustrine conditions.

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