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Ottawa-Bonnechere Graben

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Map of the Ottawa-Bonnechere Graben

The Ottawa-Bonnechere Graben (also known as the Ottawa Graben) with its branch the Timiskaming Graben, is an ancient rift valley in the Canadian Shield of Northeastern Ontario and Quebec, Canada. This rift valley was formed when the Earth's crust moved downward about a kilometer between two major fault zones known as the Mattawa and Petawawa faults. These ancient faults are still active and occasionally release stress in the form of earthquakes, such as the 1935 Timiskaming earthquake[1] and the 2000 Kipawa earthquake. The length of the graben is about Template:Unit km.[2]

The Ottawa-Bonnechere Graben runs from the Ottawa–Montreal area on the east to near Sudbury and Lake Nipissing on the west. On the east, it joins the Saint Lawrence rift system, a half-graben which extends more than 1000 km along the Saint Lawrence River valley and links the Ottawa and Saguenay Grabens.[3][4]

The Template:Unit km segment of the Ottawa-Bonnechere Graben west of Ottawa was the first to be recognized as a graben. Since than, it has been traced west to Lake Nipissing, and northwestwards from the confluence of the Mattawa and Ottawa Rivers up the valley of the latter stream to Lake Timiskaming and the Montreal River valley. This latter branch is the Timiskaming Graben. At the rifts' western termini, the main faults split into divergent smaller faults.[2] The graben has been interpreted as a Late Proterozoic to Early Paleozoic failed arm of the Iapetus Ocean, the precursor to the Atlantic Ocean.[3][2] The main Ottawa-Bonnchere Graben is associated with collapse of the regional carbonate platform and formation of deep water shale basins by ~452 mya (million years ago); similar events formed the Temiskaming Graben ~449-451 mya.[5] These grabens were reactivated during the breakup of supercontinent Pangaea some 150 mya.[6]

Geology

Three of the central Monteregian Hills (from left: Mont Saint-Hilaire, Mont Rougemont and Mont Yamaska) viewed from space.

Since the Late Proterozoic to Early Paleozoic, erosion has removed the volcanic peaks, exposing a number of relic volcanic pipes, such as Callander Bay and the Manitou Islands in Lake Nipissing.[7] These features are subterranean geological structures formed by the violent, supersonic eruption of deep-origin volcanoes. Batholiths and dikes were also exposed by erosion, such as the Timber Lake, Mulock, West Arm, Powassan and Bonfield batholiths.[7] The expressions of a thick pile of dominantly mafic, bimodel volcanics and the Tibbit Hill volcanics in the Humber Zone of the Quebec Appalachians are believed to be related to the formation of the Ottawa-Bonnechere Graben.[2] The precise age of these volcanics is unknown but they are either early Cambrian and late Precambrian.[2] This volcanism was probably coeval with the emplacement of the Grenville dike swarm.

Minor but significant igneous activity occurred during the Mesozoic era, including kimberlite emplacement during the Jurassic period, and the development of alkalic intrusions along the Ottawa-Bonnechere Graben and elsewhere in Ontario. This second episode of alkalic volcanism occurred along the eastern part of the graben in the early Cretaceous. The products of this event are the Monteregian Hills in Montreal, Quebec. These are thought to have formed as a result of the North American Plate sliding westward over a long-lived center of upwelling magma called the New England hotspot,[8] and is the eroded remnants of intrusive stocks. These intrusive stocks have been variously interpreted as the feeder intrusions of long extinct volcanoes, which would have been active about 125 million years ago,[9][2][10] or as intrusives that never breached the surface in volcanic activity.[11] Of all these features, Mont Saint-Hilaire is the best known as a source of rare specimens.

Along the northern side of the Ottawa-Bonnechere Graben lies a dramatic escarpment that forms the southern edge of the Gatineau Hills. This escarpment, called the Eardley Escarpment, makes this part of the graben an attractive location for rock climbers and hikers, offering a beautiful view of the relatively flat fields below, which extend to the Ottawa River.

On or near a branch of the Ottawa-Bonnechere Graben lies the Brent impact crater.[7] It is Template:Unit km in diameter and the age is estimated about 400 million years (Early Devonian). The impact crater, which was first recognized in 1951 from aerial photographs, formed in Precambrian gneisses. [12] Geophysical and diamond drilling investigations show that the crater has a present depth of about Template:Unit m but is partly filled with sedimentary rocks with a thickness of about Template:Unit m.[12] The rocks beaneath the crater floor are thoroughly fragmented over a depth of about Template:Unit m. Like the similar Pingualuit crater, the Brent crater is attributed to the high speed impact of a giant meteorite. It is calculated that the impact released energy equaling 250 megatons of TNT and occurred when this area was probably covered by a shallow sea.

Ottawa Valley

Ottawa river crossing the Ottawa valley near Ottawa city. At the front, skirts of the Gatineau Hills makes up part of the southern tip of the Canadian Shield

The Ottawa Valley is the valley that lies in the central and at the eastern end of the Ottawa-Bonnechere Graben, surrounding the Ottawa River for the west-east portion of its path through the Canadian Shield from Mattawa to Hawkesbury. Because of the surrounding shield, the valley is narrow at its western end, then becomes increasingly wide (mainly on the southern Ontario side of the river) as it progresses eastward. Approximately 1.3 million people reside in the valley (and along its tributaries), of these the majority, around 80% reside in Ottawa, the remainder on the north side of the Ottawa river, in Quebec. The National Capital Region area has just over 1.1 million inhabitants in both provinces.

Near the city of Ottawa, the Ottawa Valley merges with the St. Lawrence Valley to the south to create a delta of flat farmland stretching unbroken from the Ottawa River to the Saint Lawrence River as far east as the island of Montreal, where the two rivers meet. This area is sometimes referred to as the "Lower Ottawa Valley", in contrast with the "Upper Ottawa Valley" west of Ottawa, but the name is not common, and most people think of the Ottawa Valley as only the upper portion.

Because the Canadian Shield comes nearly to the Ottawa River on the north (Quebec) side of the valley, most settlements and transportation routes are on the southern Ontario side. From west to east, the major Ottawa Valley communities are Mattawa, Deep River (with nearby Chalk River, the site of Canada's nuclear reactor program), Petawawa (a major Canadian military base), Pembroke (where Samuel de Champlain landed briefly), Renfrew, Arnprior, Ottawa (the nation's capital), Rockland, L'Orignal, Hawkesbury and Rigaud.

Language

English and French are both commonly spoken throughout the Ottawa Valley on both sides of the river. Regional English accents are rare in Canada, but because of its isolation (before the arrival of the railways) and also through the mixture of the dominant French, Irish and Scottish populations, the valley at one time developed a distinctive dialect referred to as the Ottawa Valley Twang. Many traces of it can still be heard today, especially in the valley's more isolated western portions.

Tourism

See also: Ottawa River Waterway

Tourism has become one of the main industries of the Ottawa Valley, after the bust in the timber industry. Pursuits such as skydiving, tree-to-tree zip lining, whitewater rafting, camping, biking, canoeing, driving, hot air ballooning, ATV'ing, golfing and hiking draw visitors from all over Canada and abroad. (Source: Canadian Geographic)

Facts

Famous People

Among the well-known people who hail from the Ottawa Valley, are former governor-general and broadcaser Adrienne Clarkson, Alanis Morissette, Margaret Atwood, Lorne Greene, Bruce Cockburn, Peter Jennings, Matthew Perry, Dan Aykroyd, Mark Redman, Tom Green, Rich Little, Jason Hodgson, Paul Anka and Princess Margriet, sister of Queen Beatrix of the Netherlands.

Many Ottawa natives have excelled in the athletic world, particularly winter sports. Barbara Ann Scott was world figure skating champion and won the gold medal at St. Moritz, Switzerland in 1948. Skier Ann Heggtveit won a gold medal at the 1960 Winter Olympics in Squaw Valley, California. Elizabeth Manley won the silver medal for women's figure skating at the Calgary Winter Olympics in 1988. The Clifford Family has long been associated with skiing in the Ottawa area.

Linda Thom won Olympic gold at the 1984 Summer Olympics in Los Angeles. Francis Amyott, from the Britannia Club, won the single canoeing event when it was held for the first time at the Berlin Olympic Games in 1936.

Two Ontario premiers came from the Ottawa Valley - Premier Howard Ferguson (Kemptville) in the 1920s and Premier Dalton McGuinty (Ottawa), who became premier in 2003.

Hockey Country

The Ottawa Senators public relations office call Ottawa and the Valley "hockey country". Indeed it is the home not only of the once mighty Senators, which folded in 1934 and came back in the 1990s, but also of such famous NHL builders as Tommy Gorman and Ambrose O'Brien. With the Senators' arena Scotiabank Place located near Highway 417, which links Ottawa with the Valley, residents of the Upper Ottawa Valley can easily access the games.

The Ottawa Valley's Renfrew Millionaires, the creation of lumber baron O'Brien, was a small-town professional hockey team that won the league championship in 1910. Ottawa and the valley are also the home of such outstanding players as Aurel Joliat, Frank "King" Clancy, Frank Boucher and Denis Potvin; the latter was the star defenceman of the New York Islanders dynasty of the late 1970s. Ottawa's Brian Kilrea holds the record as the Ontario Hockey League's longest-serving coach with a record number of games behind the bench of the Ottawa 67's junior hockey team. The 67's themselves are something of a legend, having a loyal following that results in sellout games almost every time they step on the ice.

Geography

The Ottawa Valley covers over 7,645 square kilometres. Some 12,800 years ago, glaciers retreated from what is now the Ottawa Valley region, leaving the area covered by the by the Champlain Sea for thousands of years. Ten thousand years ago the water retreated and land emerged. More than half of the Ottawa Valley is now wilderness. Renfrew County, located in the heart of the Ottawa Valley, is the largest county in Ontario. (outside of "districts", administrative regions in Northern Ontario). There are over 900 lakes and four major river systems in the Ottawa Valley. Ottawa itself is at the confluence of three rivers. These are the Ottawa, Gatineau and Rideau rivers.

The River

The Ottawa River is 1,271 kilometres long. Its source is Lac Capimitchigama in Quebec.The Ottawa River was first navigated and settled by the Huron, Algonquin, Iroquois and Outaouais people. The Algonquin people called the Ottawa River “Kitchissippi”, which means “Great River”. The Algonquin word Kichesippirini means "Big River People". The name Petawawa comes from the Algonquin language meaning “where one hears a noise like this.”

Valley Twang

The mixture of the accents of the Valley’s French, Irish and Scottish populations created a regional dialect that came to be called the Ottawa Valley Twang, still evident among the inhabitants of the Valley.

Flora and Fauna

More than 400 species of animals live in the Ottawa Valley. The white trillium, which grows throughout the Ottawa Valley, has been Ontario's provincial floral emblem since 1937. Its white blossom is associated with peace and hope. White pine, the Ontario provincial tree, was the most commercially important tree during the heyday of the logging industry in the 19th century. It was exported to Europe and used for building the masts of sailing ships. Winter was the best season for cutting timber as trees fell more easily when their sap wasn’t running and ice and snow made it easier to drag the timber. Spring was the season when the loggers would “drive” the logs downriver.

Historical Notes

Samuel de Champlain spent the years between 1613 and 1615 traveling the Ottawa River with Algonquin and Huron guides. In charting the new land Champlain inaugurated the route that would be used by French fur traders for the next 200 years.*Between 1847 and 1879 a “horse railway” was used to portage passengers from the Ottawa River steamboat in a horse-drawn car for 5.5 kilometres along the wooded shore, around the Chats Falls, near Fitzroy Harbour, to another steamboat to continue their journey upriver.

Other Facts

  • The Counties of Prescott and Russell County, in the Ottawa Valley, has the highest concentration of francophones in Canada, living west of Quebec.
  • The small town of Perth, located in Lanark County, has been called one of the 'prettiest towns in Ontario'and is famous for its crafts and artistic community.
  • The town of Almonte is the hometown of Dr. James Naismith, the inventor of basketball. It is also the home of renowned sculptor, Tait MacKenzie. Kent Huskins, who played with the 2007 Stanley Cup Champion Anaheim Ducks, is from Almonte. Huskins brought the Stanley Cup to Almonte in the off-season.

Rivers

The Ottawa-Bonnechere Graben contains numerous rivers. Along the Deep River Reach, the Ottawa River flows along the Mattawa Fault which marks the northern edge of the Ottawa-Bonnechere Graben. Following the retreat of the glaciers from the area at the end of the last ice age, the Ottawa River valley was flooded by an arm of the Atlantic Ocean known as the Champlain Sea. Fossil remains of marine life have been found in marine clay formed drainage and the presence of large bogs in some ancient channels of this river. Another consequence was the formations of large deposits of a material commonly known as Leda clay; these deposits become highly unstable after heavy rains. Numerous landslides have occurred as a result, most notably at the abandoned townsite of Lemieux on June 20, 1993.

The Mattawa River lies along the northern edge of the Ottawa-Bonnechere Graben. It is Template:Unit km in length and flows east from Trout Lake east of North Bay and enters the Ottawa River at the town of Mattawa.

The central and northern sections of the Petawawa River lie inside the Ottawa-Bonnechere Graben. It is Template:Unit km in length and starts at Butt Lake in northern Algonquin Provincial Park and flows east, emptying into the Ottawa River at Petawawa.

The Bonnechere River lies mostly inside the rift valley. It is Template:Unit km in length and starts from Algonquin Provincial Park and flows southeasterly through Renfrew Country, emptying into the Ottawa River east and south of Renfrew, Ontario.

Lakes

Lake Nipissing lies at the western section of the Ottawa-Bonnechere Graben. Unlike most large lakes, it is relatively shallow, with an average depth of only Template:Unit m. The shallowness of the lake makes for many sandbars along the lake's irregular coastline.

Lake Timiskaming lies in the Timiskaming Graben, which is the branch of the Ottawa-Bonnechere Graben. It is Template:Unit km in length and covers an area of almost 295 km2 (114 sq mi). While the water level is only Template:Unit m above sea level, the lake is in places up to Template:Unit m deep.

Communites

Many communities in northeastern and eastern Ontario lie in the Ottawa-Bonnechere Graben. More than 28 communities lie along the Ottawa River, some of these include: Notre-Dame-du-Nord, Témiscaming , Ville-Marie, Mattawa, Deep River, Petawawa, Pembroke, Fort-Coulonge, La Passe, Braeside, Arnprior, Quyon, Constance Bay, Aylmer, Hull, Ottawa, Gatineau, Orleans, Masson, Rockland, Thurso, Papineauville, Montebello, Fassett, L'Orignal, Hawkesbury, Rigaud, Hudson, Oka, Vaudreuil-Dorion and Pincourt.

History

The depressions formed by the graben across the rugged Canadian Shield were a spillway for the Great Lakes after the last Ice Age.[13] Later they became a thoroughfare for exploration and trade. These depressions now contain the Ottawa River and its tributary the Mattawa, which rises at Trout Lake near Lake Nipissing. The latter is the source of the French River, which drains into Lake Huron. This water route, with few portages, connected Lake Huron and the Saint Lawrence River by a much shorter route than through the lower Great Lakes. It was the mainline of the French-Canadian voyageurs engaged in the fur trade; they took canoes on the waterways along this route from Montreal to the upper Great Lakes and the pays d'en haut-- the "upper country" in the old Northwest.[13] [14] The valley of the Ottawa and Montreal Rivers and Lake Timiskaming was also part of a branch route to James Bay in the days of the fur brigades.[15] The valleys are now used by more modern forms of transportation, including the Canadian Pacific Railway and the Trans-Canada Highway.[16]

After the arrival of European settlers in North America, the Mattawa River was an important transportation corridor for native peoples of the region and formed part of the water route leading west to Lake Superior in the days of the fur trade. Canoes travelling north up the Ottawa turned left to enter the Mattawa, reaching Lake Nipissing by way of "La Vase Portage", an Template:Unit km stretch of water and portages. In the 19th century, the river provided access to large untouched stands of white pine. The river was also used to transport logs to sawmills. While logging is still an important industry in this region, almost the full length of the river has been designated as a Canadian Heritage River, and as such, its shores are now protected from further development and logging. Today, the river and lakes are mainly used for recreation.

See also

References

  1. ^ "Ottawa-Gatineau Deep time". Geoscape Canada. Natural Resources Canada. 2007-10-25. Retrieved 2007-12-15. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  2. ^ a b c d e f Kumarapeli, S. (1981), Origin and development of the Ottawa Graben, Smithsonian/NASA Astrophysics Data System, retrieved 2007-12-15 {{citation}}: External link in |publisher= (help), pages 114, 115, and 116.
  3. ^ a b Tremblay, Alain; Lemieux, Yvon (2001), "Supracrustal Faults of the St. Lawrence rift System between Cap Tourments and Baie-Saint-Paul, Quebec" (PDF), Current Research 2001-D15, Geological Survey of Canada, retrieved 2007-06-20
  4. ^ "Map". Retrieved 2007-12-15.
  5. ^ Sajal, Sharma (2005-09-27). "Records of Punctuated Tectonism in Platform-Interior Graben Systems (Ontario, Canada) Far-Flung from Contemporaneous Taconic Orogenesis in the Northern Appalachians" (PDF). Calgary, Alberta: searchanddiscovery.net. Retrieved 2007-12-16. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Poster presentation at AAPG Annual Convention, Calgary, Alberta, June 19-22, 2005, and abstract.
  6. ^ The Ottawa Bonnechere Graben Retrieved on 2007-11-18
  7. ^ a b c "Background Geology of the North Bay area". Retrieved 2007-12-15.
  8. ^ "Inferred track of the Great Meteor hotspot". Retrieved 2007-11-16.
  9. ^ "A Hundred-Million Year History of the Corner Rise and New England Seamounts". Retrieved 2007-11-16.
  10. ^ "The Monteregian Hills: Igneous Intrusions". Geoscape Montreal. Natural Resources Canada. Retrieved 2006-11-16.
  11. ^ "Geology of Gault Nature Reserve, Mont St. Hilaire". McGill University. Retrieved 2007-12-16.
  12. ^ a b Currie, K.L.; Shafiqullah, M. (1967-08-12)), "Carbonatite and Alkaline Igneous Rocks in the Brent Crater, Ontario", Nature, 215: 725–726, doi:10.1038/215725a0, retrieved 2007-12-15 {{citation}}: Check date values in: |date= (help); More than one of |work= and |journal= specified (help)
  13. ^ a b "Natural Areas Report: Mattawa River". National Heritage Information Center. Ontario Ministry of National Resources. 2005-06-05. Retrieved 2007-12-15. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  14. ^ Morse, Eric (1979). Fur Trade Routes of Canada. Minoqua, WI: NorthWord Press. pp. 48–61. ISBN 1-5597-1045-4. (pages 48-61)
  15. ^ Morse, Eric (1979). Fur Trade Routes of Canada. Minoqua, WI: NorthWord Press. pp. 67–69. ISBN 1-5597-1045-4. (pages 67-69)
  16. ^ Geological Highway map (PDF), retrieved 2007-12-15. Lake Nissiping area, showing C.P.R., Highway 17, and other routes.
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