For continental divides in general, see Continental divide.
The Continental Divide of the Americas
, or merely the Continental Divide
or Great Divide
, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from, (1) those river systems which drain into the Atlantic Ocean (including those which drain via the Gulf of Mexico or the Caribbean Sea), and (2) along the northernmost reaches of the Divide, those river systems which drain into the Arctic Ocean (including those which drain into either the Arctic or Atlantic Oceans via Hudson Bay).
There are other continental divides on the North American continent, however the Great Divide is by far the most prominent of these because it tends to follow a line of high peaks along the main ranges of both the American and Canadian Rocky Mountains, at a generally much higher elevation than the other divides.
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CONTINENTAL DIVIDE TICKETS
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Geography
The Continental Divide of the Americas begins at
Cape Prince of Wales,
Alaska, the westernmost point on the mainland of the Americas. The Divide crosses northern Alaska into the
Yukon, then zig-zags south into
British Columbia via the
Cassiar Mountains and
Omineca Mountains and northern
Nechako Plateau to
Summit Lake, north of the city of
Prince George and just south of the community of
Mcleod Lake. From there the Divide traverses the
McGregor Plateau to the spine of the Rockies, following the crest of the
Canadian Rockies southeast to the 120th meridian, from there forming the boundary between southern British Columbia and southern
Alberta.
The Divide crosses into the
United States in northwestern
Montana, at the boundary between
Waterton Lakes National Park and
Glacier National Park, and bisects both parks. The Divide heads south towards
Butte, then west to the
Bitterroot Range, where it forms of the eastern third of the state boundary between
Idaho and Montana. The Divide crosses into
Wyoming at
Yellowstone National Park and continues south-southeast into
Colorado, then western
New Mexico.
It enters
Mexico along the crest of the
Sierra Madre Occidental through the
Mexican states of
Chihuahua,
Durango,
Zacatecas,
Aguascalientes,
Jalisco,
Guanajuato,
Querétaro,
México, the
Federal District,
Morelos,
Puebla,
Oaxaca, and
Chiapas; thence through southern
Guatemala, southwestern
Honduras, western
Nicaragua, and western/southwestern
Costa Rica, and southern
Panama.
The Divide continues into
South America, where it follows the peaks of the
Andes Mountains, traversing western
Colombia, central
Ecuador, western and southwestern
Peru, and eastern
Chile (essentially conforming to the Chile-
Bolivia and Chile-
Argentina boundaries), southward to the southern end of
Patagonia and
Tierra del Fuego.
In North America, a pair of secondary, non-mountainous divides further separate other river systems that drain into the Arctic Ocean and those that drain into
Hudson Bay,
James Bay, and
Ungava Bay) which open into the
North Atlantic from those which drain into the Atlantic Ocean to the south of
Labrador (including those which drain via the
Great Lakes and
Saint Lawrence Seaway).
Triple points
Triple Divide Peak, in
Glacier National Park, Montana, is the point at which two of the principal continental divides in North America converge, the Great Divide and the
Northern Divide. From this point, waters flow to the Pacific Ocean, the Atlantic Ocean via the Gulf of Mexico, and the
Arctic Ocean via
Hudson Bay. Most geographers, geologists, meteorologists, and oceanographers generally consider this point to be the hydrological apex of North America. This is the
only
place on earth where two oceanic divides meet, i.e. where waters from a single point area feed into three different oceans. This status of Triple Divide Peak is the main reason behind the designation of Glacier-Waterton International Peace Park as the "Crown of the Continent" of North America.
Another triple divide or
triple point
occurs in Canada on a prominent peak directly on the border between
Alberta and
British Columbia, called
Snow Dome because the
Columbia Icefield completely covers the summit.
[1] From this peak, water flows into the Pacific Ocean via the
Columbia River system; the Arctic Ocean via the
Athabasca River and
MacKenzie River systems; and
Hudson Bay via the
North Saskatchewan River system. Canadians generally consider Snow Dome to be the hydrological apex of North America because they consider Hudson Bay to be an extension of the Atlantic Ocean, and also because Snow Dome is higher than Triple Divide Peak.
[2] The IHO,
International Hydrographic Organization, lists Hudson Bay as part of the Arctic Ocean)
In fact, there are such triple divide points wherever any two continental divides meet.
[3] North America can be considered to have five major drainage systems: into the Pacific, Atlantic and Arctic Oceans, plus Hudson Bay and the Gulf of Mexico. Within this system there are four continental divides and three triple points, the two mentioned previously and a third near
Hibbing, Minnesota where the
Northern Divide intersects the
Eastern Continental Divide.
[4] Since there is no true consensus on what a continental divide is, there is no real agreement on where the triple points are.
[5] However, the main Continental Divide described in this article is a far more distinctive geological feature than the others and its two main triple points are much more prominent.
Hiking Trail
The
Continental Divide Trail follows the divide through the U.S. from the
Mexican border to the
Canadian border. A less-developed Canadian extension called the
Great Divide Trail continues on through five
National Parks of Canada and six
provincial parks to end at Kakwa Lake in northeastern British Columbia.
[6]
Exceptions
Many
endorheic regions in North America complicate the simple view of east or west, "ocean-bound" water flow. The
Great Basin of the western United States, the
Valley of Mexico and
Bolson de Mapimi in Mexico, the
Tularosa Basin in New Mexico and Texas, and the
Salton Trough are examples of internally draining areas. In these cases, water often drains to low basins, where
sedimentation and
evaporation form
salt lakes,
playas,
salt flats, and
alkali flats.
On the
Llano Estacado in Texas and New Mexico, many thousands of seasonal
playa lakes form during wet months, an average of one per square mile. This region is very flat, and water mostly evaporates before draining.
Zuni Salt Lake is one example of a larger, seasonal
maar which does not drain to an ocean. There are a number of seasonal lakes of this sort in North America. In areas of
karst topography (such as northern
Florida), isolated drainages can also occur. The
Great Divide Basin in Wyoming has no natural outlet except as
groundwater, and hence it lies between the Atlantic and Pacific watersheds, being part of neither. Water from the
North Two Ocean Creek in Wyoming flows into both oceans.
Although
Panama's isthmus provides clear division between Atlantic and Pacific, the boundaries between the Atlantic and Arctic Oceans in
Baffin Bay are not well defined, rendering the easternmost portion of this divide arbitrary.
Images
See also
- Continental Divide Trail
- Great Divide Trail
- Eastern Continental Divide
- Lemhi Pass
- List of railroad crossings of the North American continental divide
- Laurentia
- Laurentian Divide (Northern Divide}
- Valparaiso Moraine
References
- Snow Dome
- Snow Dome - The Hydrological Apex of North America
- Triple Divide Points and North American Drainage Basins
- Minnesota State Map Collection
- Continental Divides in North Dakota and North America
- Hiking Canada's Great Divide Trail