A Narrative of Montreal Geology (II)
Myth of Montreal (as told by the rocks)
BY NATHAN FERGUSON AND MICHAEL KISHCHUK
Part two of blog series on Montreal geology. The oldest histories of a place are written not in words, but in rocks. What do the rocks of Montreal tell to those who try to listen? How can we translate their stories, and share this lithic narrative? Co-written by an anthropologist and a geologist, this series includes an introduction and two complementary myths of Montreal. Part three forthcoming.
Montreal skyline. Photo taken from Mont Royal Park by Maya Lamothe-Katrapani.
The oldest histories of a place are written not in words, but in rocks. What do the rocks of Montreal tell to those who try to listen? How can we translate their stories, and share this lithic narrative? Co-written by an anthropologist and a geologist, we present here an introduction and two complementary myths of Montreal. These are origin stories as told by strata and sediment. Drawing upon scientific understanding and a deep sense of place, this is an early effort in convergent poetry, inspired in equal parts by swarm ethnography, standpoint feminism, convergent evolution, and the prolific artistry of biodiversity. We hope you enjoy.
What kind of narrative for a narrative of Montreal geology?
In the beginning, there was a joining. Two continents came together, sutured by a keloid scar of rock. The Grenville orogeny raised a range of mountains, Himalayan in stature, and greatly deformed in their depths. The combination of continents made the planet binary: ocean or rock. Supercontinent Rodinia. As the force of the collision faded, and mountains eroded to rounded hills, the continents split apart, drifting. An ocean opened between them, ancestor of the Atlantic. Iapetus. Offshore, piling up like dust on the continental shelf, sediment accumulated. First sand, the rubble of mountains, carried by rivers. Then silt and mud, drifting down through the depths, settling on the shelf. Finally coral and ooids, carbonate growing and precipitating. Sandstone, shale, limestone; sediments were laid over the deformed remains of mountains, like pages in the archive of the planet. Submarine deposition on the St. Lawrence Platform. Then a series of orogenies — Taconic, Acadian, Alleghenian — closed the Iapetus and lifted new mountains skyward. Montreal lay at the margin of this uplift, and though only distantly affected, it was now shadowed by new peaks. These folded and banded rocks became the spine of Pangea. Appalachian Mountains. Later, below the surface, magma intruded through layers of sedimentary rock, enormous plutons that rose like globules in a lava lamp. Though never emerging at the surface as volcanoes, they baked and fractured the surrounding rock. The long narrow fractures filled with molten rock, which crystallised as it cooled, and eventually the bulbous subterranean magma chambers solidified too. They became syenite and gabbro, coarse-grained and crystalline, resistant to erosion. Gradually, as the surrounding land wore away, these cooled plutons became prominent, islands of rock above a sea of soil and forest. Monteregian Hills.
Much later, glaciers descended from the Pole, vast lobes of ice sweeping southward across the continent. They stripped away soil, and bedrock too, bulldozing the terrain, scraping smooth everything except the resistant Monteregian Hills. Laurentide glaciation. The great weight of the ice sheets, kilometres thick, depressed the continent, pushing it downward into the viscous mantle like a laden boat. When the planet warmed and the glaciers retreated, they left behind moraines of till and drumlins of gravel. Then seawater flooded the lowered basin. Champlain Sea. Relieved of its frozen cargo, the continent slowly rebounded, and saltwater turned brackish turned fresh, as a sea became an estuary became a river, draining off the edge of the gradually rising continent. The current carved elongate islands from the glacial sand and mud, and its banks became fertile soil. St Lawrence River.
Today, the river flows through old seafloor sediments, across the platform of a much older, lithified ocean. Bounded by the remains of ancient mountains on both sides, Mount Royal rises above the stream of the St Lawrence, the resistant remnant of a cooled pluton. Made from welded continents and from the bottom of the sea, shaped by the forces of mountain-building and by the movement of ice, a mountain on an island in a river. Montreal.
A technical chart taken from the article "Geology of Montreal" (1985), published by Boyer et al. in Environmental and Engineering Geoscience. Their own description of the chart can be seen at the bottom of the image.
Credit: By Boyer et al., "Geology of Montreal," in Environmental and Engineering Geoscience 22, no. 4 (pp. 329-394), 1985.
