Download Topic 2 = Physical Geography

Topic #2
Physical Geography of the United States
The Platform for American History
Introduction to Physical Regions
When the first Europeans set foot on the continent of North America they encountered the eastern
edge of a land mass which encompassed a vast and varied topography.
The region of North America that is today known as the United States is composed of nine [9]
major physical or topographic regions, each of which is divided into two or more sub-regions.
Because the geography of any area has a direct bearing on the history that subsequently unfolds
on it, it is reasonable to take a brief look at the physical nature of the land mass that the
Europeans were about to occupy and subdue and the place to begin is on the east coast where
the Northern Europeans first attempted to settle.
Region #1: The Coastal Plain: Atlantic Coastal Plain & Gulf Coastal Plain
The Coastal Plain
•Composed of two sub regions -
•the Atlantic Coastal Plain and
•the Gulf Coastal Plain
•Extends along the edge of the continent from Cape Cod at the northern end for
approximately 2,200 miles to
the mouth of the Rio Grande in Texas.
•Varies in width from a few miles in the north to more than 500 miles along the Mississippi
River.
•North of Cape Cod there is no Coastal Plain - the bare glaciated rock of the continent directly
meets the Atlantic Ocean.
•At the Mississippi River, the Gulf Coastal Plain extends inland along the broad alluvial plain
as far as Cairo,
Illinois.
•The dividing line between the two sub regions is Florida
•The Coastal Plain very low relief, generally less than 100 feet
•Composed of sedimentary deposits created on floodplains by old, broad, meandering
streams and rivers.
•The coast is marked by wave cut cliffs and benches, lagoons, sand bars and sand dunes.
•Site of first Northern European colonies.
•Rivers are navigable and were the early transportation & trade routes.
•The region has long been known for agricultural activities.
Atlantic Coastal Plain
•Soil is generally sandy and, except for certain places is not particularly fertile.
•Rainfall is adequate and a rich and varied agriculture developed quite early.
•Grains and garden crops were common in the north and central Atlantic region.
•Rice, indigo, tobacco and later cotton were early staple crops further south.
The Gulf Coastal Plain
•The alluvial soils of Gulf Coastal Plain region, especially the Mississippi bottom lands and
the Texas black prairies, are extremely rich.
•By the time this region was extensively occupied, sugar cane and cotton were the main
staple crops.
Region #2: The Piedmont Plateau
•Rolling highlands west of the Atlantic Coastal Plain stretching from approximately Trenton,
New Jersey south and west into Alabama
•As its name implies pied = foot, mont = mountain, it lies at the foot of the Appalachian
mountain complex to the west.
•Piedmont is higher in elevation than the Coastal Plain [some 200 feet in New Jersey and over
1,800 feet in Georgia] and is generally somewhat cooler and drier than the lowlands.
•Soils are deep and rich in many areas so agriculture is still prominent - grain in the north
and tobacco and later cotton in the south.
•First cattle country in the colonies.
Hogs were raised in the rolling hills of the Piedmont and
in the northern portion, dairying was practiced from early times.
Piedmont – The Fall Line
•The rivers within the Piedmont province are navigable above and below the Fall Line, which
is a zone of rapids and waterfalls along the eastern edge of the Piedmont.
•The more resistant rocks underlying the area cause the rivers to plunge downward to the
lower Coastal Plain.
•One result of this Fall Line was the development of a series of cities.
These began as small
villages where goods were transshipped and portaged around the falls,
The Piedmont Plateau
•As industry developed, the access to the sea and the abundance of water power at these
sites saw these villages grow into major cities.
•From north to south along the Fall Line - Trenton, Philadelphia, Wilmington, Baltimore,
Washington, Richmond, Raleigh, Columbia, Augusta and Columbus
Region #3: The Appalachian Mts.
•Rise to the west of the Piedmont.
•A very old, eroded, and dissected system of mountain ranges and ridges separated by
elongated valleys.
•Bordered by plateaus on the east and west.
•Created by the collision of what are today the continents of Africa and North America more
than 200 million years ago. (Supercontinent called Pangea)
•For the last 200 million years wind and water have worn them down to the low eroded ridges.
•The New England portion of the region was extensively glaciated
•Local names for various parts of the system are both descriptive and familiar - The Green
and White mountains in New England, the Alleghenies and Catskills in New York, the
Cumberlands in Kentucky and Tennessee, the Blue Ridge in Virginia, the Great Smokies in
North Carolina.
• Rivers have created many fertile and famous valleys, such as the Connecticut Valley in New
England, the Hudson and Mohawk valleys in New York, the Lehigh Valley in Pennsylvania, the
Shenandoah Valley in Virginia and The Tennessee Valley.
•The western portion of the system is a long plateau that slopes toward the plains of the
center of the continent. This is known as the Allegheny Plateau in the north and the
Cumberland Plateau in the south.
•Once routes, such as the Cumberland Gap, were discovered through the North-South ridges
which enabled east-west movement, the region became noted for it’s agriculture and
commerce.
•Many deposits of minerals are scattered throughout the system, notably coal, found all
through the system, oil in Pennsylvania, marble and limestone, to name a few, have turned
several of the valley areas into highly developed industrial areas
Region #4: The Canadian [Laurentian] Shield
The Superior Uplands
•West and East of the Great lakes are two areas - the Superior Upland and the Adirondack
Mountains that are a very small part of the enormous Precambrian Canadian Shield
[sometimes called the Laurentian Shield].
•Every continent has one or more shield areas - the Scandinavian Shield in Europe, the
Deccan Shield in India, the Siberian Shield in Asia, the Brazilian Shield and the Congo region
of Africa.
•These regions are made up of extremely old rocks, surmised by geologists to be the original
cores of the continental land masses.
•In all cases they have been worn down, often by continental ice sheet glaciation and are
covered with lakes and glacial till.
•They are also universally rich in minerals.
•The United States has only these two small pieces of the Shield, but the benefits have been
significant.
•This region was a major source of copper until WWI.
•The major U.S. source of iron ore is the iron rich Mesabi Range located in the Superior
Uplands.
•Mined since the 1890s, and geologists estimate that we will be able to mine it for the next
200 years.
Adirondacks
•The Adirondacks are more widely known for their recreational activities, but there are
deposits of Iron ore and Titanium found here as well. These deposits of iron ore are
especially important due to their proximity to Pittsburgh.
Region #5 Interior Plains = The Central Lowlands & The Great Plains
Interior Plains
•Most of the United States between the Appalachians and the Rocky Mountains, a distance of
1,500 miles, is covered by a vast region called the Interior Plains or Lowlands.
•Largest of all U.S. physical regions.
•divided, approximately along the 100th meridian, into the Central Lowlands to the east and
the Great Plains lying between the meridian and the Rocky Mountains.
•Several huge rivers -including
the Missouri, the Ohio, the Tennessee, the Platte and the
Arkansas all flow into the Mississippi, the “Father of all waters”
•The Mississippi flows South into the Gulf of Mexico draining approximately 1/3rd
of the
North American Continent into the Gulf at one point - the mouth of the Mississippi.
•The low relief and the river system of this massive interior lowland has had a number of
important influences on the economic and settlement history of the United States.
•In addition to the vast agricultural potential it provided, fully half the country could be
crossed without encountering significant topographic barriers to movement.
The Central Lowlands
•One of the world’s richest agricultural and industrial regions.
•The portion of this region lying north of the Missouri-Ohio rivers was extensively glaciated in fact these rivers were created as they carried glacial melt water along the front of the ice
sheet.
•Thousands of years of heavy forest [now gone] east of the Mississippi and thick prairie
grasses west of the Mississippi, created the rich soils, which along with adequate rainfall,
have made this area one of the world’s most fertile natural farming regions.
•This area includes the Corn Belt, the dairy belt, the hog belt, and the wheat belts of the Midwest and extensive orchard areas near the Great Lakes.
•Many manufacturing areas, mostly connected to the agriculture of the region, have
developed in the area bounded by Cincinnati and St. Louis in the south and the Great Lakes
in the north.
•South of the Missouri-Ohio river system are the rolling plains of the Kentucky Bluegrass
region and the Nashville Basin of Tennessee.
•The southwestern portion of the Central Lowlands extending into Texas is called the Osage
Plains.
The Great Plains
•Region of limited rainfall - the climatic classification is Steppe or grasslands, which means
that the region averages less than 20 inches of rainfall per year.
•They slope upward toward the Rockies to the west and most areas lie well above sea level
and are short on rainfall and water for irrigation.
•The near the 100
th
Meridian is the “Tall Grass Prairie.” The farther west the shorter the
grass.
•Early maps denote it as the “Great American Desert,” as early farmers could not utilize it
because of the tough sod covering of the region.
•Until recently, the major activity throughout this vast expanse of grass was cattle raising this was the scene of the post Civil War “Cattle Kingdom.”
Region #6: The Interior Highlands = The Ozark Plateau & Ouachita Mountains
Interior Highlands
•West of the Mississippi, the southern border of the Interior Plains is an uplifted area of
Plateaus and Mountains called the Interior Highlands.
•Composed of two units:
Ozark Plateau in the north and the Ouachita Mountains in the
south. The two parts are separated by the Arkansas River. Some mineral deposits - mainly
lead and zinc, but agriculture and recreation seem to be more important.
•From early times, the hot springs and spas have attracted tourists, especially in the hot
summer months, as this area is higher and therefore cooler than the Gulf Coastal Plain
regions immediately to the south.
•Hot Springs, Arkansas was the first national park to be established in 1832.
•The Ozark region has long been cloaked in mystery and isolation - noted for “hillbillies &
moonshine.”
•Interior Highlands was the focal point of a Dynasty of Western Outlaws which lasted for
some 60-70 years. From Quantrell’s Raiders of the Civil War era up to the 1920’s outlaw
bands used this area as a hideout and staging area for their activities
Region #7: The Rockies
•The Rocky Mountains, the “Continental Divide,” the “Backbone of the Continent,” is a
system of rugged mountain ranges and valleys that extend from Canada through the
continental U.S. into Mexico.
•Roughly Parallel to each other and trending north-south, these ranges reach heights of over
14,000 feet and
•except for occasional passes, the most famous of which is South Pass in southern
Wyoming, are a significant barrier to east -west transportation and commerce.
•The Rocky Mountain system is composed of three main subdivisions –
•the Northern Rockies,
•the Wyoming Basin and
•the Southern Rockies
•Unlike the old, worn down Appalachians, the Rockies are still actively growing - a result of
the westward migration of North America.
•The dividing line between the Rockies and the Great plains is striking.
In most places along
this line the mountains rise thousands of feet in just a few miles. The only exception to this
rapid elevation change in found in the Wyoming Basin.
•Historically a barrier, the Rockies gained early fame for the Fur Trade and later the area the
site of discoveries of great deposits of gold, silver, lead and copper.
•Deposits of oil and natural gas were discovered in the Wyoming Basin and several other
locations. Today, in addition to forestry and minerals, the Rockies are famous for parks and
recreational activities
The Northern Rockies
•The Northern Rockies extend from north and west of the Wyoming Basin into Canada, and
contain some of the more famous and spectacular scenery of the Rockies.
•In the geologic past, this portion of the Rockies was subjected to extensively glaciated
which produced the sharp peaks generally associated with mountain ranges like the Tetons,
the Bighorn, Wind River and Bitterroot Mountains, the Sawtooth, Coeur d’Alene, Lewis and
Salmon ranges.
•Farther to the east smaller ranges like the Yellowstone and Black Hills are considered to be
part of the Rocky Mountain system
The Wyoming Basin
•The Wyoming Basin is in reality an extension of the Great Plains into the middle of the
Rocky Mountain System.
•This lower region gradually rises toward the crest of the Rockies in a broad gentle cloud
shrouded trough or saddle called South Pass.
•This was and is historically the main route through the central part of the Rockies to the
Pacific Coast.
•The Basin is noted for oil and natural gas deposits
The Southern Rockies
•The Southern Rockies lie south of the Wyoming Basin and extend into Mexico.
•They consist of a series of mountain ranges and valleys.
•The ranges include the Colorado Front Range [the location of Pike’s Peak], the Laramie,
Wyoming, Wasatch and San Juan ranges and the Sacramento and Sangre de Cristo
Mountains.
Region #8: Intermontane Region = Columbia Plateau, Colorado Plateau & the Great Basin
•In the 1840s and early ‘50s pioneers and gold seekers thought that they had it made when
they passed through South Pass. They thought the gold fields of the Pacific were just a hop,
skip and jump away.
•They were in for two major, nasty surprises:
•The first was the barren deserts of the Great Basin , the basin of the Intermontane Basin
and Plateaus province.
•The second was the rugged, snow capped Sierra Nevada,
•The Intermontane Basin and Plateaus region is made up of two plateaus, the Colorado
Plateau in the south and the Columbia Plateau in the north. These two plateaus are separated
by a lowland called the Great Basin.
•The rugged topography of this province is composed of a series of mountains, high
plateaus, deeply incised river gorges and barren deserts.
•It presented formidable barriers to westward expansion.
•Early activities in this region were limited mostly to mining
.
The Columbia Plateau
•Covering approximately 100,000 square miles, the Columbia Plateau is one of the world’s
largest areas of lava flow.
•The Plateau is bordered on the west by the volcanic Cascade range, on the east by the
Rocky Mountains and on the south by the Great Basin,
•The Modoc Plateau in northeastern California is on the southern edge.
•The lava flows of this region [the most recent only 1000 years old] reach thicknesses of up
to 10,000 feet.
•These flows have been dissected and gouged by two major rivers, the Columbia and the
Snake and the resulting canyons posed major transportation problems to the western
movement.
•In the central part of the Plateau, to further glacial outwash created a series of broad steep
sided watercourses called coulees. These coulees are as much as 50 miles long and 1000
feet deep
•The Columbia Plateau is semi-arid because it is in the rain shadow of the Cascade Range.
•In many parts of the plateau, the lava flows are so recent that soils are very thin to
nonexistent. However, where the volcanic material has had time to break down, the soil is
rich and in an extensive agriculture has developed in eastern Washington and Oregon
The Colorado Plateau
•The Colorado Plateau is a very different structure.
•It is a formation of deeply eroded sedimentary rocks, chiefly sandstones and limestones that
cover approximately 150,000 square miles.
•The plateau has a general elevation in excess of one mile above sea level.
•It has been carved into by the Colorado River and its tributaries, creating deep [up to 1 mile]
and in some cases wide chasms such as the Grand Canyon.
•These canyons posed major problems for transportation.
•The area is arid and agriculture is limited to those areas where irrigation is possible.
•Much of the land has been relegated to reservations - Indian and Military
The Great Basin
•The Great Basin, or Basin and Range Province occupies the center of the Intermontane
province.
•Most of this feature lies in the current state of Nevada; however, it extends into eastern
California and southwestern Utah.
•Lying in the rain shadow of the Sierra Nevada the region is arid.
•Geologically, the Great Basin is a series of fault block ridges with valleys between them.
•Minerals, including gold and silver [the Comstock Lode] were discovered here and
historically, the main reason for settlement was mining.
•The Great Basin can best be characterized by one term - Interior Drainage.
This means that
from Southern Nevada north to the Columbia Plateau and from the Sierra Nevada east to the
Rockies, no stream or river flows out of this region to the sea.
•All water flows inward and except for evaporation stays there.
•Because evaporation is the only way for water to leave this region, every standing body of
water is saline - with the Great Salt Lake being the saltiest – and every flat or gathering point
for runoff has a salt flat or Playa.
•Death Valley, the lowest point on the North American Continent is on the western edge of
this region.
•There are several rivers that flow into this region.
The best known is the Humboldt, which
flows across eastern Nevada and ends drying up in the swamp of the Carson Sink. Others
include the Walker and the Truckee
Region #9: Pacific Coast Ranges & Valleys
•Composed of three mountain ranges - the Coast Ranges, The Sierra Nevada and the
Cascade Range,
•Three major lowlands or valleys - The Great Central Valley [California], the Willamette Valley
[Oregon] and the Puget Lowland [Washington].
•The valleys are very similar to each other,
•Each of the mountain areas is distinctly different in nature from the others.
The Sierra Nevada
•The Sierra Nevada is a tilted fault block with a gentle western face and a steep escarpment
on the east face.
•It runs 400 miles from approximately Highway 36 in the north to Bishop in the south.
•The western slope is well watered and covered with lush green forests, while the eastern
slope is arid.
•Historically the Sierra Nevada posed serious problems for transportation, but when gold was
discovered on the western slopes in 1848, thousands of people managed to get over or
around this barrier.
•Gold is still mined in the Sierra but forestry and recreation in parks, such as Yosemite, are
more important at present.
•is a volcanic formation that begins at Highway 36 at it’s southern end [Mt. Lassen] and
extends northward through central Oregon and Washington into Canada.
•While it is designated a mountain range, it is more correctly a long narrow plateau or ridge
with massive volcanic peaks scattered along it.
The Cascade Range
•The Volcanoes include Lassen and Shasta in northern California, McLaughlin, Crater
Lake/Mazama and Hood in Oregon , Rainier, St. Helens and Baker in Washington and Mt.
Garibaldi in Canada.
• only dormant, not extinct.
In the last century Lassen and St. Helens erupted and there is
continual seismic activity around most of the others.
•Historically and presently, the major activities in the Cascade Range were/are forestry,
grazing and recreation
The Coast Ranges
•The Coast Ranges are a very young mountain system.
•They are approximately a mere 2 million years old, and are the result of the westward drift of
the North American continent shoving it against and over the pacific plate.
•This westward movement has fractured and buckled the western edge of the continent,
causing numerous faults, such as the San Andreas, throughout California.
•As the North American Plate has ridden over the Pacific Plate, it has scraped mud and
sediment from the surface of the Pacific Plate and added them to the western margin of the
continent.
•This has produced a series of young ridges and valleys, composed of unconsolidated
materials that are highly subject to erosion and have a tendency to collapse or slump
[landslides].
•The Coast Ranges are notable for their lack of minerals.
•Agriculture is found in valleys such as Sonoma and Napa.
•Forestry and grazing are the main activities.
The Valleys
•The interior lowlands –
•While there are smaller valleys of note – such as the Napa Valley
•the Central Valley of California, the Willamette Valley in Oregon, and the Puget Sound
lowland in Washington are the only extensive lowlands near the West Coast.
•The three lowlands/valleys are troughs of mud - sediments deposited by the streams and
rivers that flow through them.
•In some cases these sediments are very deep
•Near the confluence of the Sacramento and San Joaquin rivers in central California, the
muds are 8,000 -10,000 feet thick
•The Great Central Valley of California has the Sacramento and the San Joaquin rivers and
their tributaries,
•The Willamette Valley, in Oregon, has the Willamette River
•The Puget Lowland, in Washington, is really part of Puget Sound that has been filled in with
alluvium, possibly as glacial outwash from the ice sheet which occupied much of the area
north of the Columbia River 75,000 years ago.
•The soils found in each of these valleys are incredibly rich, and from the earliest occupation
by Americans have produced an abundance of agricultural commodities.
•Crops vary from the cotton in the drier San Joaquin Valley, to rice in the Sacramento Valley,
to orchards and berries in Oregon and Washington