Geoscience Reference
In-Depth Information
pointing into the wind. The inside of the U is hollowed out as wind picks up sand grains and moves them to
the crest, depositing them on the far side. In this manner, the dune moves, or is said to wander, while maintain-
ing its shape. The lee side of the Greenwich dune contains a natural plant succession, from marram to shrub
growth such as bayberry, and, finally, to wind-stunted white spruce. Three large barachois ponds are also loc-
ated behind the wandering dunes. The brackish waters of the ponds attract a variety of waterfowl and other
marsh birds such as American bittern and pied-billed grebe. Savannah sparrows, short-eared owls, and horned
larks also haunt the dunes.
Warm and Cold
Living near the Northumberland Strait, for four months of the year I look onto an Arctic-like icefield, blind-
ingly white against an azure or pewter sky. In certain years, pans of ice may persist into May. The Gulf of St.
Lawrence differs from other large estuaries along the North Atlantic coastline in that it is ice-covered in winter.
This ice has three principal sources: locally formed icefields; ice from the St. Lawrence River and estuary; and
ice, including small icebergs, that move from the Labrador Shelf into the gulf via the Strait of Belle Isle. Ice
begins to form in sheltered areas in December and increases rapidly throughout January. By the end of January,
ice covers about half of the gulf, and the entire gulf is blanketed in pack ice by the end of February. The ice
breaks up rapidly in the spring as the prevailing westerly winds and water currents carry it southeastward out
of the gulf toward the Scotian Shelf.
This ice plays an important ecological role, as it becomes a breeding platform for three species of seals:
harp, gray, and hooded. Of these harp seals are the most numerous. They belong to the group of hair seals,
family Phocidae, which are characterized by negligible external ears, hind flippers which do not turn inward,
and the absence of underfur—precisely the three features that distinguish them from the eared seals, Otariidae.
In addition, harp seals are distinguished by having white-coated young.
