Continental divide
This article is about continental divides in general. For the Atlantic/Pacific divide, see Continental Divide. For the movie, see Continental Divide (movie)A
continental divide is a line of elevated
terrain which forms a border between two
watersheds such that
water falling on one side of the line eventually travels to one
ocean or body of water, and water on the other side travels to another, generally on the opposite side of the
continent. Because the exact border between bodies of water is usually not clearly defined, the continental divide is not always definite for any continent (The
International Hydrographic Organization's publication
Limits of Oceans and Seas defines exact boundaries of oceans, but it is not universally recognized). Moreover, some rivers empty into deserts or inland seas, and thus do not end up in the oceans.
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Continental Divides in North America |
*
North America has four continental divides:
**The
Great Divide, also called the
Continental Divide separates the watersheds of the
Pacific Ocean from those of the
Atlantic or
Arctic Oceans. It runs from the
Seward Peninsula in
Alaska, through western
Canada along the crest of the
Rocky Mountains to
New Mexico. From there, it follows the crest of
Mexico's
Sierra Madre Oriental and extends to the tip of
South America. It is crossed by the
Panama Canal**The
Northern Divide, or
Laurentian Divide, separates the watershed of the
Atlantic Ocean from that of the
Arctic Ocean**The
St. Lawrence Seaway Divide separates the
Great Lakes watershed from the rest of the Atlantic Ocean watershed. Two
canals cross the divide: The
Chicago Sanitary and Ship Canal crosses the
Chicago Portage and connects
Lake Michigan to the
Mississippi River watershed. The
Erie Canal connects
Lake Erie to the
Hudson River watershed.
**The
Eastern Continental Divide separates the watershed of the
Gulf of Mexico from the
Atlantic Ocean. It runs from northern
Pennsylvania down the
Appalachian Mountains to the tip of
Florida, dividing the Atlantic from the
Gulf of Mexico. The city of
Atlanta sits atop this divide.
*In
South America, the
Continental Divide lies along the
Andes, but the divide does not run along the highest peaks of the mountain system.
*
Australia has less distinct ocean boundaries and fewer prominent mountain ranges, making it hard to define a single divide. Much of the interior of the continent drains into the
endorheic Lake Eyre Basin.
*It is similarly difficult to distinguish the continental divides of
Europe and
Asia, because of the large number of distinct bodies of water into which their rainfall drains (for example, the
Mediterranean Sea and its various
lobes, the
Atlantic Ocean, the
North Sea, the
Baltic Sea, the
Arctic Ocean and the
Black Sea with Europe).
*The most significant continental divide in
Africa is that between the watersheds of the
Nile and the
Congo, passing through the area of the
African Great Lakes. Between the Congo and the
Sahara, a vast area drains into the endorheic
Lake Chad, so puncturing the
Atlantic-
Mediterranean divide. The
Mediterranean-
Indian Ocean divide is punctured in
West Africa by the endorheic lake systems of the
Great Rift Valley; in the south of the continent the divide between the Atlantic and Indian Oceans snakes between the watersheds of the Congo,
Zambezi,
Limpopo and
Orange Rivers, with the
Okavango terminating in the
Kalahari Desert.
* As the interior of the continent receives very little precipitation, and that in the form of
snow, and also as it is entirely surrounded by the
Southern Ocean,
Antarctica is not generally considered to have a continental divide. The
Transantarctic Mountains divide the
ice streams draining
West Antarctica into the
Ronne Ice Shelf, toward the
Pacific and into the
Ross Ice Shelf, from those draining
East Antarctica toward the Atlantic and Indian Oceans.
*
Drainage basin*
Continental Divide Trail Alliance*
nationalatlas.gov*
Divide.pdf -
Continental Divides in North Dakota and North America by Mark A. Gonzalez. Excellent article on America's
other continental divides.
*
Map of drainage basins in Canada
