Geography
[edit]
Situation and political divisions[edit]
Map of Bas-Saint-Laurent with regional counties
The Bas-Saint-Laurent is a region in the East of Quebec, delimited to the north by the Saint Lawrence River, to the south by New-Brunswick and Maine, to the east by the Gaspé Peninsula and to the west by Côte-du-Sud. It extends over an area of 28,319 km2 (10,934 sq mi), with 22,141 km2 (8,549 sq mi) of land area, which represents a bit less than 2% of the total area of Quebec, however, this area also represents 10% of the inhabited area of Quebec, or about half the land area of Switzerland.
The region is divided into eight Regional county municipalities (RCM), which contain 130 municipalities. Bas Saint-Laurent contained 200,462 inhabitants in 2011, of which 55,400 were in its most populous RCM, Rimouski-Neigette. Otherwise, the least populous RCM of the region is Les Basques, with only 9,000 inhabitants in 2011, a number which decreased by 1,300 since 1996, making it also the RCM with the highest annual rate of population decrease of the region, with a rate of 9.6% between 2006 and 2011.
Forested areas and waterways dominate the land use of Bas-Saint-Laurent. The region counts 100,071 km2 (38,638 sq mi) of mixed forests, 4,918 km2 (1,899 sq mi) of coniferous forests and 6,177 km (3,838 mi) of waterways. Humid lands only covers 58 km2 (22 sq mi) and the land devoted to agriculture covers 2,819 km2 (1,088 sq mi), while developed areas represent only 143 km2 (55 sq mi), which equals to 0.5% of the total land area of the region.
Geology[edit]
Even if an isolated area of Cambrian and Precambrian rocks exist in an area of the Chic-Choc Mountains, the region belongs generally to the geologic province of the Appalachian Mountains, which covers an area of 3,000 km2 (1,200 sq mi), between Alabama and Newfoundland. The marks of two episodes of mountain-building, the Acadian orogeny and the Taconic orogeny, have shaped the land.
During the first orogeny, the subduction of the oceanic plate created a volcanic chain in the Iapetus Ocean, off the coast of Laurentia during the Cambrian period. The magma surfacing mixed with the sediments originating from the continental erosion and the volcanic arc of islands got gradually closer to the continent to the subduction. The two collided 450 million years ago and formed a chain of immature mountains, the Taconic Mountains, their nappe covers a part of the Saint Lawrence Lowlands.
This first zone, which follows the river today, is known as Humber's zone. Dating from the Ordovician, this bedrock is composed primarily of sedimentary rocks : sandstone, mudrocks and conglomerates. South of this zone, the Gaspé belt is the remnant of a second mountain formation during Siluro-Devonian times. Around 430 million years ago, the Taconic mountains eroded and created sediments that deposited at a shallow depth. As Laurentia and the micro-continent Avalonia deformed and raised the sedimentary deposits and volcanic rocks and created a second chain of mountains, the Acadian Chain, which superposes itself on the Taconic Chain.
Seismicity[edit]
Main article: Charlevoix Seismic Zone
The estuary of the Saint Lawrence river in front of the Charlevoix region is one of the most active seismic regions in the east of Canada. Five earthquakes of a magnitude superior to 6 have occurred in history, in February 1663, December 1791, October 1860, October 1870 and February 1925. The distribution of these earthquakes indicates a concentration in the estuary, near La Malbaie and Rivière-du-Loup.
Surveys and the establishment of a seismometer network were conducted in the 1970s and allowed to circumscribe the seismically active area in an area of 30 km (19 mi) on 85 km (53 mi) along the Saint Lawrence River, this zone includes the towns of La Malbaie, Baie-Saint-Paul and La Pocatière. The seismic data indicates that an earthquake happens on average every 36 hours in the Charlevoix-Kamouraska zone. They are concentrated in the Precambrian bedrock under the Logan line and the Appalachian Mountains, at a variable depth between 30 km (19 mi) deep and the surface
Another seismic area located in the Gulf of Saint Lawrence, in a triangle between the towns of Matane, Baie-Comeau and Sept-Îles. However, this seismic area is less active than the one uphill, as only an average of sixty earthquakes occur each year and has not had a destructive earthquake in history. An earthquake of magnitude 5.1 occurred in 1944 east of Godbout and another of the same magnitude occurred on the 16 March 1999, its epicentre was located at about 60 km (37 mi) south of Sept-Îles.
Topography[edit]
Inselbergs in Saint-André-de-Kamouraska
The topography of Bas-Saint-Laurent has two main elements : the plateaus of the Appalachian Mountains, called Notre Dame Mountains, and the lowlands in the fine stripe of land along the Saint Lawrence river. These are separated by an intermediate area of ridges and foothills which meld with the plateaus. The Notre Dame Mountains, are a group of small mountains with summits reaching between 600 and 700 m (2,000 and 2,300 ft) high. the landscape is sometimes interrupted by valleys, like the Témiscouata valley or Matapedia Valley. These two parallel valleys allow access to The Maritimes, Maine and Chaleur Bay.
The littoral, spanning across 320 km (200 mi) is composed of riverside land of altitudes ranging from 0 to 250 m (0 to 820 ft) above sea level. This area has a depth of 5 km (3.1 mi) before reaching the mountains in the west of the region, but reaches 25 km (16 mi) in the vicinity of Rimouski, only to shrink again in the eastern limits of the region. This riverside land disappears entirely between the municipalities of Sainte-Félicité and Grosses-Roches. In the western part of the territory, this littoral plain is interrupted by inselbergs, ridges reaching that can reach 200m in height, typical of the riverside land of Bas-Saint-Laurent
In the Quaternary, the region was marked by glaciation. the Wisconsin glaciation caused the crust to sink by 200 m (660 ft) in the vicinity of Rimouski. When the end of the glaciation started in 18,000 BP, it opened a sound in the Saint-Laurent valley, isolating the glacier covering Bas-Saint-Laurent from the one covering Côte-Nord. The isostatic rebound created an inland sea, the Sea of Goldthwait, which flooded the region under at most 200m of water in the area around Rimouski.
The withdrawal of the Sea of Goldthwait was gradual, 2,000 years ago the isostatic rebound stabilised at around 1 mm (0.039 in) per year, the withdrawal of the water formed a number of narrow streaks of emerged land near the riverside between Rivière-du-Loup and Rimouski, known today as Île aux Lièvres, Île Verte, île aux Basques, île du Bic and île Saint-Barnabé.
Hydrography[edit]
Matapédia River in Causapscal
The estuary of the Saint Lawrence river, to the north of the region, plays a primary role in the region. It is divided in two regions split at Cacouna: west of Cacouna, it is called a medium estuary, while east of the municipality it is called a maritime estuary or lower estuary.
The region is relatively poor in fresh water, since lakes and rivers only count as 1.5% of the land area. It possesses two hydrographic regions, the first holds all the streams that pour into the estuary of the Saint-Lawrence river and the region of Chaleur Bay and Percé, whose streams flow south into New-Brunswick and Maine. These regions influenced the layout of the administrative areas of Bas-Saint-Laurent, by setting limits to some regional county municipalities.
The largest drainage basins of the region are located in the south of the territory. These are the drainage basins of the Matapedia River (3,328 km2 [1,285 sq mi]) and Madawaska River (2,861 km2 [1,105 sq mi]). Ranking third, the drainage basin of the Cascapédia River of 1,701 km2 (657 sq mi), half of this basin is located within the limits of the administrative region. Among the notable rivers pouring into the Saint-Lawrence, we can count the Mitis River (1,812 km2 [700 sq mi]), Matane River (1,692 km2 [653 sq mi]), Rimouski River (1,621 km2 [626 sq mi]), Rivière du Loup (1,046 km2 [404 sq mi]) and Trois Pistoles River (966 km2 [373 sq mi]).
Bas-Saint-Laurent counts 2,417 lakes, of which 90% do not exceed an area of 20 ha (49 acres). About 30% of them are situated in the RCM of Rimouski-Neigette. The two largest lakes of the region are Lake Témiscouata (66.82 km2 (25.80 sq mi)) and Lake Matapedia (38.07 km2 [14.70 sq mi]), significant human settlement on their shore has taken place, as well as along the roads going through their valleys. These lakes also distinguish themselves by their north west and south west orientation, compared to most of the other lakes of the region which prefer to follow the orientation of the creases and breaks of the Appalachian Mountains.
Climate[edit]
Winter in Saint-Paul-de-la-Croix
Bas-Saint-Laurent, like the rest of Quebec, is a Nordic American territory. The Quebecois geographer Louis-Edmond Hamelin categorized the region in his pre-north area, second of the five zones of his map of nordicity zones.
The oceanic influence of the estuary of the Saint Lawrence River has a small influence on the climate of the region, making it more alike to the climate of meridional Quebec, than with "Nordic" towns like La Sarre in Abitibi or Roberval, Quebec in Saguenay-Lac-Saint-Jean, located at the same latitude than the town of Matane. However, the climate of Bas-Saint-Laurent is of continental type, with a "great amplitude and no dry periods".
The French geographer Raoul Blanchard described the temperature variations between winter and summer as "brutal". During the winter, which lasts for five months, the cold freezes the lakes and rivers and transforms the estuary into a "vast prairie of ice".
The oceanic influence, while it mitigates the cold of the winters, cools the summers. The average temperature in July in Rimouski inferior by 4 degrees to the one recorded in Quebec. To this, the wind of the north west adds humidity and cold.
Rainfall is abundant and consistent throughout the year. The region currently receives annually 800 to 1,200 mm (31 to 47 in) of rainfall, of which between 250 and 360 cm (98 and 142 in) is snow. The oceanic influence is less present inland, where slightly warmer temperatures in the summer and slightly colder in the winter are recorded.