Physical Geography of the United States and Canada
*Look at pages 117, 122 & 123 in the textbook.
*Canada is the 2nd largest country in the world, and the United States
are 3rd. Put together, the cover more than 7 million square
miles, or about 13% of the Earth’s land area (or just under 4% of all
the Earth’s surface).
*There are four major physiographic regions in the United States and
Canada: the Western Uplands, the Interior Lowland, the Eastern
Highlands, and the Eastern Coastal Plain.
*The westernmost region is the Western uplands system, a series of high
mountains and plateaux (and valleys and lowlands mixed in) that stretch
from Mexico to Alaska. They were formed relatively recently
(between 140 and 65 million years ago) by tectonic and volcanic
activity, and they still have a number of active volcanoes—the most
recent major explosion was at Mount Saint Helens in 1980, the most
deadly in US history, which blew off the entire side of the mountain,
killing 57 people and destroying 185 miles of highway. Since
October 2004, the mountain has been exhibiting minor volcanic activity
*Unfortunately, most of this region, especially near the Pacific, experiences significant earthquake activity.
*This region includes the Pacific Ranges: the Sierra Nevada, the
Cascade Range, the Fraser Plateau and the Coast Range (in Canada), and
the Alaska Range, which includes the highest mountain on North America,
Mount McKinley in Alaska (20,320 feet above sea level). The Rocky
Mountains are also part of this region, and run from New Mexico to
Alaska, with some peaks over 14,000 feet above sea level.
*The western side of these mountains is generally very pleasant, thanks
to the maritime effect and the good side of the orographic
effect. Southern California enjoys a Mediterranean climate, with
dry summers and mild, wet winters. This lets it grow oranges and
cotton, and other crops that require such conditions.
*Farther north, Northern California, Oregon, Washington, British
Columbia, and parts of Alaska enjoy a Marine West Coast climate, and
parts of Washington are so well-watered that they actually produce a
temperate rain forest, where the redwood tree (and other tall trees)
*It is fairly temperate and pleasant within the Pacific Ranges, too,
and many of the valleys, particularly in the Central Valley of
California, are very good for agriculture.
*Between the Pacific Ranges and the Rockies are a series of
plateaux. Because of the orographic effect, most of this area is
fairly dry. Most of it has a steppe climate, and parts of it are
*In Washington and Oregon is the Columbia Plateau, formed by one of the
largest flows of lava basalt in the world. It is watered by the
Columbia River, and, when irrigated, is valuable for
*The Colorado Plateau is in Western Colorado, which has been worn down
by erosion, features the Grand Canyon. It is suitable for some
ranching and grazing.
*The Basin and Range area in Nevada, Arizona, and parts of California,
was created by normal (or block) faulting. This is where Death
Valley, the lowest and hottest point in the United States can be found
(in California); it is 282 feet below sea level, and reached a US
record temperature (2nd hottest worldwide) of 134°F on 10 July,
1913 (the hottest temperature ever was 136.4 °F in Libya in 1922).
*The space between the Pacific ranges and the Rockies also includes the Great Salt Lake.
*The Rocky Mountains serve as the western continental divide for the
United States and Canada. East of the Rockies is a vast area of
interior lowlands. In the United States, this is the Mississippi
watershed. In Canada, some of this area’s rivers flow into the
Arctic Ocean, some flow into Hudson Bay, and some flow into the Great
Lakes and thence into the Atlantic Ocean down the Saint Laurence River.
*The Mississippi-Missouri River system is the fourth longest in the world and by far the longest in North America.
*The northern part of this region has largely been defined by glacial
erosion, while the Southern part has been defined by water erosion and
*During the Ice Ages (the last of which ended about 10,000 years ago),
glaciers scoured much of the topsoil and loose rocks off of large
stretches of Canada and the northern United States. This pressed
the ground flat, to a greater or lesser degree, and in many places
carved out lakes.
*In Canada, the flattest and most scoured region (which lost most of
its best soil) is the area around Hudson Bay; it is known as the
*Minnesota calls itself the land of 1,000 lakes (and Manitoba calls
herself the land of 10,000 lakes), and most of these lakes came from
glacial action, as did the Great Lakes themselves.
*Most of the soil scoured off of the Canadian Shield and elsewhere
ended up in the central United States, but some was left everywhere
there was glacial activity.
*Some of this soil was washed away by erosion, and ended up along the Mississippi and its tributaries in their flood plains.
*Because there are no major mountain ranges in this area, climate is mostly determined by latitude.
*In the far north of this region, of course, it is mostly tundra, and
then sub-arctic land that mainly supports coniferous forests.
Farther south, however, the land becomes very productive.
*Immediately east of the Rocky Mountains it is still steppe, and
suitable for ranching. Many rivers rise in the Rockies, however,
and even this area, especially in the Canada’s breadbasket provinces,
is suitable for growing wheat and corn.
*Moving away from the Rockies one finds humid continental and humid
subtropical climates in the USA and Canada. All of these have
good growing seasons and temperatures suitable for growing most crops
and raising most livestock.
*About the only things that cannot be grown are citrus fruits and some
other tropical crops, and in the continental regions, cotton and rice
and a few other warm-weather crops do not do well.
*In the northern parts of the United States, a lot of the corn grown in
this region is actually raised to feed dairy cows, as they will eat
green corn picked after a shorter growing season than most humans
like. An exception to this is the area right around the Great
Lakes, where the lake effect (sort of like the Maritime Effect)
moderates the temperature somewhat—this area tends to grow fruit trees.
*The best soil in the entire area is found in the region between Iowa and Ohio
*On the other hand, some of the soil in the South is not as rich as
that farther north, because, with the warmer weather, organic matter in
the soil rots faster and nutrients are exhausted more quickly.
*This area feeds the United States, Canada, and large parts of the rest of the world.
*In the United States, the Eastern Continental Divide is the crest of
the Appalachian Mountains, and the area around the Mountains is a
distinct region unto itself, although it is less complex than the
*The Appalachian Mountains were formed about 350 million years ago (or
possibly longer) through tectonic folding action when they were at the
centre of the super-continent Pangaea. At that time, they were
part of the same mountain range that now also forms the Atlas Mountains
in North Africa. Other continental collisions over the centuries
have folded them further. They have been wearing out ever since,
and today their highest point is Mount Mitchell in North Carolina, at
6,684 feet above sea level.
*The Appalachian Mountains stretch from Alabama up to Newfoundland, although there are some breaks along the way.
*Because the Appalachians are relatively low in elevation, they do not
significantly alter the local climate, so they are mostly humid
subtropical and humid continental, although they do experience humid
continental climates at lower latitudes than the areas around them.
*There are a number of smaller systems within the Appalachians.
In addition to the mountains themselves, there are a series of plateaux
to the west, including the Allegheny or Cumberland Plateau and the
Catskills area of New York, as well as an area of raised land on the
east, called the Piedmont (or foothills).
*The local range of the Appalachians is the Unaka Range, sometimes
known (especially farther South) as the Great Smokey Mountains.
The Unaka Range is part of the Blue Ridge, which runs from Georgia to
*Between the Blue Ridge and the western plateaux lies the Great Valley,
sometimes described as a ridge and valley system, because it has a
series of ridges and valleys raised by tectonic folding. It runs
from the Saint Laurence River to Alabama. Around here, this is
where the Holston River runs down to the Tennessee. The Great
Valley system also includes the Shenandoah Valley of Virginia, one of
the most fertile regions in Appalachia. The Great Valley is
important historically because it was the route many people took to
settle the west, coming down into Virginia and Tennessee from
*Historically, erosion meant that this area had poorer soil than
surrounding regions while the mountainous nature of the region made
transportation difficult, so, although the climate tended to be good,
the area was largely passed over by settlement after the late 1700s and
early 1800s, and the area did not develop as other places did.
*East of the Appalachian Mountains, and south of them along the Gulf
Coast, is the Eastern Coastal Plain. It stretches from New Jersey
down into Southern Texas.
*This was the area of the earliest settlement in the United States,
because it was closest to Europe, and, being relatively flat, was easy
*The edge of early settlement was typically the edge of the tidewater, and later the fall line.
*The Tidewater is a region in which the rivers near the ocean are
affected by the tides, in some cases so much that the flowing of water
in and out and high and low tide would be enough to move boats up and
down the river.
*The Fall Line is the place where the Piedmont drops off to the Coastal
Plain; it is the point where a river has not eroded the land down to
(or near) sea level. At or beyond the fall line, river become
shallow, rocky, or have waterfalls (hence, ‘fall line’). Many of
the USA’s great cities (Philadelphia, Baltimore, Washinton, D.C.) lie
on the fall line as a place where goods could be transferred from land
transportation to ships.
*In almost all of this region the climate is humid subtropical, even
giving way to some tropical savanna in southern Florida. This is
due in part to the presence of the Atlantic Ocean and its warm
currents. This region can (in lower places) see palm trees,
citrus and other warm-weather fruit trees, cotton, rice, and other
crops that require warm (and usually wet) weather.
*The main downside of the Atlantic Ocean’s proximity is the possibility of frequent hurricanes throughout this region.