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Laurentian Divide

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A drainage divide , water divide , ridgeline , watershed , water parting or height of land is elevated terrain that separates neighboring drainage basins . On rugged land, the divide lies along topographical ridges , and may be in the form of a single range of hills or mountains , known as a dividing range . On flat terrain, especially where the ground is marshy , the divide may be difficult to discern.

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20-642: The Laurentian Divide also called the Northern Divide and locally the height of land , is a continental divide in central North America that separates the Hudson Bay watershed to the north from the Gulf of Mexico watershed to the south and the Great Lakes - St. Lawrence watershed to the southeast. Water north of the divide flows to Hudson Bay; water south of the divide and also south of

40-875: A key problem in such canals is ensuring a sufficient water supply. Important examples are the Chicago Portage , connecting the Great Lakes and Mississippi by the Chicago Sanitary and Ship Canal , and the Canal des Deux Mers in France, connecting the Atlantic and the Mediterranean. The name is enshrined at the Height of Land Portage on the route from the Great Lakes in the Atlantic drainage basin to

60-488: A landscape border, usually motivated by demarcating treaty -designated political boundaries, goes against nature by modifying the borderland's natural geography. For one, China's Song Dynasty built an extensive defensive forest in its northern border to thwart the nomadic Khitan people . In Chapter IV of his 1916 book The New Europe: Essays in Reconstruction , British historian Arnold J. Toynbee criticized

80-986: A major policy goal for a number of states. For example, the Roman Republic , and later, the Roman Empire expanded continuously until it reached certain natural borders: first the Alps , later the Rhine river, the Danube river and the Sahara desert. From the Middle Ages onwards until the 19th century, France sought to expand its borders towards the Alps, the Pyrenees , and the Rhine River. Natural borders can be

100-624: A source of territorial disputes when they shift. One such example is the Rio Grande , which defines part of the border between the United States and Mexico , whose movement has led to multiple conflicts . Natural borders are not to be confused with landscape borders, which are also geographical features that demarcate political boundaries. Although landscape borders, like natural borders, also take forms of forests, water bodies, and mountains, they are manmade instead of natural. Installing

120-806: Is the bifurcation of the Orinoco in the north of South America , whose main stream empties into the Caribbean , but which also drains into the South Atlantic via the Casiquiare canal and Amazon River . Since ridgelines are sometimes easy to see and agree about, drainage divides may form natural borders defining political boundaries, as with the Royal Proclamation of 1763 in British North America which coincided with

140-529: Is used in Canada and the United States to refer to a drainage divide. It is frequently used in border descriptions, which are set according to the "doctrine of natural boundaries ". In glaciated areas it often refers to a low point on a divide where it is possible to portage a canoe from one river system to another. Drainage divides can be divided into three types: A valley-floor divide occurs on

160-680: The Urstromtäler , for example, between Havel and Finow in the Eberswalde Urstromtal . In marsh deltas such as the Okavango , the largest drainage area on earth, or in large lakes areas, such as the Finnish Lakeland , it is difficult to find a meaningful definition of a watershed. A bifurcation is where the watershed is effectively in a river bed, in a wetland, or underground. The largest watershed of this type

180-695: The Black Sea and the Rienz into the Adriatic . Settlements are often built on valley-floor divides in the Alps. Examples are Eben im Pongau , Kirchberg in Tirol and Waidring (In all of these, the village name indicates the pass and the watershed is even explicitly displayed in the coat of arms). Extremely low divides with heights of less than two metres are found on the North German Plain within

200-950: The Hudson Bay drainage basin . Natural boundaries A natural border is a border between states or their subdivisions which is concomitant with natural formations such as rivers or mountain ranges . The "doctrine of natural boundaries" developed in Western culture in the 18th century being based upon the "natural" ideas of Jean-Jacques Rousseau and developing concepts of nationalism . The similar concept in China developed earlier from natural zones of control. Natural borders have historically been strategically useful because they are easily defended . Natural borders remain meaningful in modern warfare even though military technology and engineering have somewhat reduced their strategic value. Expanding until natural borders are reached, and maintaining those borders once conquered, have been

220-666: The St. Lawrence Divide flows to the Gulf of Mexico, otherwise to the Labrador Sea or via the Great Lakes and St. Lawrence Seaway to the Gulf of St. Lawrence . From the divide's junction with the Continental Divide at Triple Divide Peak , just south of the U.S. border in northwestern Montana , it runs north to just across the border then east through southern Alberta and Saskatchewan where it turns southeasterly reentering

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240-867: The Vosges Mountains in 1871 but during World War I , some Germans began to advocate for even more western natural borders—specifically ones that extend all of the way up to Calais and the English Channel —conveniently justifying the permanent German retention of those Belgian and French territories that Germany had just conquered during World War I. As an alternative to the idea of natural borders, Toynbee proposes making free trade, partnership, and cooperation between various countries with interconnected economies considerably easier so that there would be less need for countries to expand even further—whether to their natural borders or otherwise. In addition, Toynbee advocated making national borders based more on

260-442: The 48th parallel before veering north again to cross the western border of Quebec just south of Lake Abitibi . It then meanders northeasterly across Quebec to the southwestern boundary of Labrador . From there, it follows the boundary jaggedly north to Killiniq Island where it becomes the boundary between Nunavut and Labrador before reaching its terminus at Cape Chidley on the Labrador Sea . Two triple divide points lie on

280-536: The Gulf of Mexico. The other triple divide is at Hill of Three Waters near Hibbing , Minnesota , which is the junction with the St. Lawrence divide. This not a summit, but a highland plains where the watersheds of the Mississippi, Nelson and St. Lawrence River (which flows to the Gulf of St. Lawrence) meet. The eastern portion of the divide marked the original northern boundary of both Ontario and Quebec provinces at

300-473: The U.S. at the northwestern corner of North Dakota . It then continues to the extreme northeast corner of South Dakota before crossing the middle of Minnesota 's western border at the Traverse Gap . The divide then runs north and east through northern Minnesota, through Superior National Forest in the eastern tip, into Ontario . There it passes to the north of Lake Nipigon , then runs as far south as

320-799: The bottom of a valley and arises as a result of subsequent depositions, such as scree , in a valley through which a river originally flowed continuously. Examples include the Kartitsch Saddle in the Gail valley in East Tyrol , which forms the watershed between the Drau and the Gail, and the divides in the Toblacher Feld between Innichen and Toblach in Italy , where the Drau empties into

340-478: The concept of natural borders. Specifically, Toynbee criticized this concept as providing a justification for launching additional wars so that countries can attain their natural borders. Toynbee also pointed out how once a country attained one set of natural borders, it could subsequently aim to attain another, further set of natural borders; for instance, the German Empire set its western natural border at

360-812: The divide. One is at its origin on Triple Divide Peak, in Glacier National Park , Montana, where it meets the Continental Divide; this is usually considered the hydrological apex of North America. That peak divides the waters of the Columbia River watershed which flow to the Pacific Ocean from the waters of the Nelson River watershed which flow to Hudson Bay and the Mississippi River watershed which flows to

380-662: The ridgeline of the Appalachian Mountains forming the Eastern Continental Divide that separated settled colonial lands in the east from Indian Territory to the west. Another instance of a border matching a watershed in modern times involves the western border between Labrador and Quebec , as arbitrated by the privy council in 1927. Drainage divides hinder waterway navigation . In pre-industrial times, water divides were crossed at portages . Later, canals connected adjoining drainage basins;

400-577: The time of Confederation in 1867, although both have since expanded significantly northward. West of Lake Superior, the divide formed the northern boundary of the United States' Louisiana Purchase in 1803. Height of land A triple divide is a point, often a summit , where three drainage basins meet. A valley floor divide is a low drainage divide that runs across a valley , sometimes created by deposition or stream capture . Major divides separating rivers that drain to different seas or oceans are continental divides . The term height of land

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