Hills montérégiennes

The hills montérégiennes , simply so called the montérégiennes , are a series of nine Colline S aligned on a distance of approximately eighty ten kilometers in the areas of Montreal, the Montérégie and the Estrie, in the south-west of the Quebec.

Origin of the name

Mons Regius , Latin word, was used for the first time in 1903 by Frank Dawson Adams to indicate the royal mountains , that is to say the present Royal Mont and the eight other hills of geology similar located in the plain of the St. Lawrence to the east of the town of Montreal.

Thereafter, the word Mons Regius gave rise to the word montérégien to indicate a geological province gathering these formed hills of igneous rocks intrusive alkaline. The hill montérégienne the best known one is the Royal Mont today, mountain which gave rise to the island of Montreal, formerly the island of the Royal Mount, and at the town of Montreal which was built near the mountain.

The rocks which one finds in the hills montérégiennes are rare and have a composition very different from the other rocks of the Vallée of the the St. Lawrence. They are as different from the sedimentary rocks as one finds in the Assembly line of the the Appalachian Mountains located at the east of the valley of the St. Lawrence.

Covered territory

The first definition of the hills montérégiennes included/understood the mounts Royal, St-Bruno, St-Hilaire, Rougemont, St-Gregoire, Yamaska, Shefford and Brome.

The Mégantic mount was added later to the list. Although it is located in the middle of the the Appalachian Mountains, the Mégantic mount is characterized by its rock formation different from the hills which surround it. It is also necessary to take account of three intrusions: those of St-Andre and Oka to the west of Montreal, and the Iberville intrusion, close to the St-Gregoire Mount. The intrusions of St-Andre and Oka form a depression; only that of Oka is not completely hidden.

The list of the hills montérégiennes, of west in is, with their height and their age:

Royal Mount, 233 meters, 118 My with? (where My = million years)
Mount St-Bruno, 218 meters, 118 My to 136 My
Mount St-Hilaire, 411 meters? to 135 My
Mount St-Gregoire, 267 meters, 119 My with?
Mount Rougemont, 381 meters? to 137 My
Mount Yamaska, 416 meters, 120 My to 140 My
Mount Shefford, 526 meters, 120 My to 130 My
Mont Brominates, 553 meters, 118 My to 138 My
Mont Mégantic, 1112 meters, 128 My to 133 My

Geology of the hills montérégiennes

The hills montérégiennes were formed by rises of magma in the Earth's crust above a hot Point. The North-American plate moving towards the west, it resulted a series from it from hills which are aligned of west in east. The resulting geological formation includes not only the Québécois hills montérégiennes but also of the geological formations similar to the the United States and in the Atlantic Ocean.

The definition of the rocks montérégiennes is the following one: " They are igneous rocks intrusive of age Crétacé (124 My), south of the Quebec. One finds them in the form of cluster or of Dyke S along a West-east axis, between the area of Oka and the Mont Mégantic. These rocks are very distinguished from the other igneous rocks by their alkaline chemical composition (rich in Calcium and Magnésium), indicating the major origin of the magma at the origin of these roches." (Pierre Bédard, Ph.D, UQAM). Because of the major origin of the magma which formed them, these rocks contain several Minéraux rare such thaumasite, native arsenic and dawsonite.

During the formation of the hills montérégiennes, the magma which infiltrated in the Sedimentary rock of the Earth's crust is cooled inside the rock without reaching surface. In contact with the heat of the magma, the sedimentary rock was transformed into a metamorphic Roche very hard. This stage of the formation of the hills, it did not have there “hills” above the ground but only one dome of hard stone hidden in the sedimentary rock under the level of the ground.

In fact the Glacier S discovered the hills by tearing off the friable sedimentary rock which surrounded them. As the metamorphic dome of rock was very hard, it could resist the glaciers, which explains why the hills are now above the level of the ground.

On some of the hills, the glaciers succeeded in tearing off part of the cap of metamorphic rock of the dome, thus discovering the igneous Roche which is under the envelope of metamorphic rock of the hills. As the igneous rock coming from the cooling of the magma is more friable than the metamorphic rock, the glaciers could dig depressions at the top of the hills whereas the edges of the cap resisted erosion because of the hardness of their metamorphic rock. This phenomenon explains the presence of depressions and lakes at the top of several hills montérégiennes.

These depressions at the tops of the hills montérégiennes are responsible for the popular Croyance which wants that the montérégiennes are old Volcan S extinct. It anything because it there forever is obviously had of it flows of Lave of the hills montérégiennes, completely hidden under the sedimentary rock when they cooled. Nevertheless, the link of the montérégiennes is continued, in the Atlantic Ocean, by a link of volcanos in the abyssal plain of Sohm, in the west of the médio-Atlantic dorsal. The two links are aligned.

Another popular belief wants that the water of the lakes of the hills montérégiennes comes from the cast iron of the glaciers. This belief is inaccurate. The melt water of the glaciers evaporated since good a long time and it was replaced by quite ordinary rainwater!

Use by the human ones

Because of their proximity of the town of Montreal, the hills montérégiennes are very attended for recreotouristic activities. That it is for the Hiking, the Ski touring, the Alpine skiing, the Escalade, the traditional meals of spring in the huts with sugar, the Golf or the gathering of Fruit S, of the thousands of people attend them each year, with like unhappy consequence the embrittlement of the ecosystem of the hills.

The fact that they contain mineral and metals attracted mining and career S which leave enormous holes in their sides.

The hills montérégiennes are also very favourable with the culture of the apples which require a ground well drained. The Moraine deposited with the foot of the mountains by the Glacier S supports a natural drainage of the grounds which supports in its turn the culture of the apple trees.

Montérégie

The hills montérégiennes gave its name to the Montérégie which is the area of Quebec located at the south-west of the province.

As explained in the section Origin of the name , Montérégie thus draws its name from the Latin version of the name of the mount Royal ( mount Regii ). Montérégie thus draws its name… from a hill which is not in Montérégie but well in the area of Montreal. It is another cocassery of the Toponymie!

See too

External bonds

the hills montérégiennes with the Cretaceous
the hills montérégiennes in 3D

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