Evolutionary description renders the edge through the lens of a young planet that was mostly oceanic until photosynthesizing organisms began to colonize the otherwise rocky, barren shores. In the past tense, the shore was lifeless. As our earliest and most immediate ancestors evolved, the profusion of life along the shore emerged, and new lifeways proliferated within a warmer, and generally drier climate. In the present tense, tidal shores are now greatly enlarged and teeming with life of all kinds, from mollusks and algae to crabs, sea stars, barnacles, isopods, and periwinkles. Life on the edge unquestionably includes the indelible fact that forty percent of the human population lives less than 100 kilometers from the coast—millions upon millions of human residents. Across ages, life at the edge is described as rich and uncertain, prompting the rise and fall of both natural migrations and unnatural fortunes—we are all species of the edge. This refers to the long-established ecological concept that moments of overlap and interaction between adjacent ecosystems are associated with greater species diversity and biological richness. The question most fluvial scientists, legal appraisals, and homeowners faced in the past circled around that of permanence to affirm ownership: where is the edge? In the twenty-first century, the framework of change might include new questions, like: when is the edge?

The tidal landscape is ruled by the moon, sometimes entirely submerged and other times cracked and baked by the elements. The immeasurable quality of the edge enlarges as the intertidal materializes lunar time: unconsolidated sediments flank solid rock, flat-bottomed slopes are choked by mudflows, and depressions enlarge and fill between shallows. Rachel Carson reminds us that it is only along the shore, that we can actually observe and measure the progress of one of the earth rhythms. In geologic time, the beaches known to our terrestrial species only stabilized about 5,000 years ago, after the glaciers retreated and revealed hidden lands fringed by salt marshes, mudflats, beaches, estuaries, and fens. In human time, the steady rise and fall of the tidal edge is not distant—it is noticeable underfoot.

The South-shore of the Big Waterway is a landscape of geo-biological processes contoured by the great curve of the  Gaspésie. From the perspective of Big Waterway, this mid estuary, tidal river region accumulates and absorbs much of the runoff, chemicals, and shattered rock conveyed eastward, while westward winds define the movement of storms and weather that travel across the surface waters. From a watershed point of view, we are in the territory of rivulets, of hundreds of tributaries that carry freshwater to the flood- plains along stretches of cooled rigid rock that intersect rich mud- flats. From an administrative perspective, this is Bas-Saint-Laurent, a portion of the characterized by its edge.

Landscapes of retreat are defined by settlement patterns—in this case, those whose lives depend on the tidal edge, and the silty alluvial floodplains that are primarily settled by flat stretches of agricultural farmland, alternating with pockets of summer communities. Summer arrives in the Earth’s tilt, as vacationers, and their spending activity seem to chase the sun. The local population swells in summer and contracts in winter, bringing familiarity—restaurants are no longer overflowing with strangers, they are filled with neighbors and friends. The familiar is set deep in the knowledge of winter, as the change of seasons signal a recuperative time associated with the rhythm of other organisms that also benefit from hibernation and dormancy. The quiet of winter is often portrayed in poetry, painting, and music. The colder season is depicted as slow, while summer moves quickly; similarly, winter is hard, while summer is easy. This is also mirrored by the tourist economy, which amplifies the settlement pattern and marks the difference between summer households and year-round residents.