Newfoundland fiords

In various publications (A4, B8, B17, B22, B23, B28, and B30) we describe the Quaternary marine geology of Newfoundland. Coastal regions bear the imprint of glaciation, particularly the presence of fiords. Fiords on the south coast are up to 750 m deep (Bay of Exploits), and those on the north coast are commonly more than 600 m deep. These deep basins must have been excavated by the repeated discharge of ice from the interior of the island. Commonly they contain thick accumulations of stratified muds that were deposited after ice retreated to the heads of the bays. In a paper published in Boreas (B28) we described how the glaciers halted at the mouths of the south-coast fiords for up to 1500 years. These halts formed submarine moraines that date back to 14.2 radiocarbon years BP.

On the west coast, arcuate submarine moraines are found off Bonne Bay, Bay of Islands, and St. George's Bay. In these areas, the surfaces of the moraines are in shallow water, so that in some instances erosion during the early postglacial sea-level lowstand has caused erosion; these effects are best seen in St. George's Bay, where the surface of the moraine is obscured by thick deposits of reworked sand and gravel (see B22, B23).

Modern inner-shelf processes

• Mud deposition occurs mainly in inner harbours, fiords, and deep water on the shelf (e.g., Notre Dame Bay, Placentia Bay). The mud forms ponded deposits, and has an acoustically transparent appearence. In many instances, currents form banks (e.g., Bay of Islands), or sedimentary furrows: arcuate trenches up to 10 m deep.

• The impact of icebergs on the sea floor is observed in Notre Dame Bay, where the sea floor has a rugged appearence due to the presence of pits and furrows (see A4).

• Modern coastal processes include the formation of wedges of sand offshore from barriers and spits (see B8, B12).

• An almost unique processe is the formation of submarine fans that carry sand from shallow water into deep water. Examples are observed in St. George's Bay and Bonne Bay (B22, B23).

• Gas release forms pockmarks, e.g., off Burgeo, near Stephenville.

• Human impacts include submarine landslides, deposition of dredge spoil, shipwrecks (B30).

Submarine slide at Corner Brook, Bay of Islands, probably triggered by human actions