The Bay of Fundy is underlain by the Fundian Lowlands formation of Triassic sedimentary rocks. Bottom topography roughly parallels the coastline, sloping gradually away from it. The sandwaves are up to 18 m high and 183 m in length.
Deeper parts have a sandy bottom with silt and clay mixed in, and glacial till in the fringe areas.
Rock formations in the Bay of Fundy are extensions of those that make up the shoreline. This area frequently has a range of wave-like bottom features, but often exposed bedrock occurs. Oceanography Tidal circulation predominates in the area. Secondary variations on tidal circulation occur seasonally because of freshwater runoff and the proximity of the slope water front. Storm waves can also be significant.