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2/9/2015
Physical Geography
The physical landscape (natural
environment) sets the stage for
human use (cultural landscape).
Physical Landscape I
of the
United States
and Canada
Prof. Anthony Grande
©AFG 2015
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Physical Geography
Definitions
Geography: study of people living on the surface of
the earth.
Geology: the scientific study of the earth and its
processes.
Geomorphology: the study of landforms and landform
regions.
Topography: the study of a landform region’s
surface features.
We need to be aware of its parts and
mechanisms.
– geologic processes (tectonic/gradational)
– atmospheric processes (weather/climate)
– water resources (surface/underground)
– soils (formation/fertility)
– natural vegetation (a result of all of above)
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Shape and Position
of the Continents Today
Physical Geography
For the US&C need to be aware of the role of:
1. Plate Tectonics and Continental Drift and
all processes that shape the natural landscape.
North
America
2. Great Range of Latitude: from polar to topical
and its influence on climate formation, vegetation
and human response.
3. Climate Change: esp. the continental glaciation
associated with the Ice Ages (global cooling) and
present trends (global warming).
4. Water: the chief sculptor of landform features and
important for well-being of people.
5. Human Impact: effect of people and their
works on the natural landscape.
Europe
Asia
Africa
South
America
Australia
Antarctica
(not shown)
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How did they get to be shaped and positioned?
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Plate Tectonics
Theory
Plate Tectonics
Theory
 The present-day position
of the continents is a result
of a single land-mass called Pangaea being separated along the lithospheric
cracks (plate boundaries) by
 Dates from the 1960s:
• Says the lithosphere (crust + upper mantle) is broken into sections (now called plates), which
move relative to each other by
forces inside the Earth.
• The lithosphere (40-250 mi thick) is
rigid.
• It’s surface layer (crust) is com The rigidity of the lithosphere
posed of an oceanic layer
causes it to crack under
(denser rocks) and a continental
pressure from internal
layer (less dense rocks).
forces.
the movement of convection
cells within the mantle.
 Each segment has slowly
been repositioned (shifted).
– Movement of the plates
continues to occur.
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225 mya
Continental
Drift
Plate Tectonics
N.
Am.
 This movement creates:
Oldest rock units on
today’s continents line up
on the map of Pangaea.
a. Gaps allowing new crust to form >> spreading zones.
b. Forces plates against each other where they collide,
override each other and deform >> mountain building.
Similar geologic layers and fossil beds on
the continents are linked
when the continents are
brought back to their
Pangaea positions.
c. Pushes old crust back into the earth >> subduction
zones.
 It is responsible for earthquakes and volcanic activity.
 This movement created the phenomena that gives us
our present-day surface features.
N.
Am.
Note the position of North
America on each map.
TODAY
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Location of the Earth’s Plates
and Directions of Movement
Earth’s Surface without Water
Note underwater mountain ranges (which mark spreading zones),
subduction zones (areas of earthquake and volcanic activity) and the
continental shelves (areas flooded by sea level rise).
North
America
Subduction
zones
(oldest rocks)
Spreading zones
(youngest rocks)
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KEY
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Focus on North America
Because of Plate Tectonics…
• The North American plate is moving westward and
meeting resistance from the Pacific, Juan de Fuca and
Cocos plates.
– Western North America’s surface features are younger
and steeper (angular) than the Eastern North America.
– Eastern North America’s features are older and more
worn down (rounded).
• Earthquakes are more common in the west.
• Eruptive volcanic activity is exclusively a western
phenomena.
• The volcanically-formed Hawaiian Islands are not near
a plate boundary but located on a plate that is moving
over a “hot spot.”
Earthquake Zones
The San Andreas fault is the most
famous fault line of North America.
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Geologic Map
of
North America
Because of Plate Tectonics…
o The eastern coast has a wide, extensive continental
shelf and coastal plain.
o The western coast has a narrow or non-existent
continental shelf and coastal plain.
 The western coast exhibits relatively few coastal
marshes, swamps and barrier islands.
 The eastern coast has a good supply of each.
• The western coast has fewer inlets and estuaries
(important as safe, natural anchorages) than the eastern
coast.
The subsurface geology
of North America is varied
and very complex.
The continent’s
paleogeography has
changed many times.
This can be seen in its
rock record, including
remnant surface features.
from the National Atlas of the United States
From the National Atlas of the United States
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Physiographic
Diagram of
North America
The continent’s underlying
geologic structure and its
dynamic processes of
formation and change over the
eons have shaped the land
surface features of North
America.
In turn these have influenced
running water, soil formation,
natural vegetation and human
perception.
Together they create
physiographic regions.
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Physiographic
Regions
of the US&C
Based on the bedrock
geology and the surface geomorphology,
we can divide the
US&C into distinct
physical regions.
http://mapmaker.rutgers.edu/355/raisznorthamerica1000.jpeg
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From Birdsall, Regional Landscapes of the US&C
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Folding
GEOLOGIC PROCESSES
TECTONIC (building)
GRADATIONAL
1. Folding
1. Mechanical and chemical
weathering (in place)
2. Mass wasting (by gravity)
3. Agents of Erosion
2. Faulting
3. Volcanism
Folding is the crumpling of the surface upon impact
(collision; mountain building).
(reducing)
(erode → transport → deposit
take →
NATURAL PROCESSES
1.
2.
3.
4.
Mass movements (gravity)
Earthquakes (tension release)
Volcanism (heat, pressure)
Subsidence (sinking)





move
→ place )
Running water
Moving ice
Wind
Wave action
Longshore currents
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Faulting
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Volcanism
Volcanism is when the combination of great pressure
and heat is able to melt rock.
Release of stress (pressure) is faulting.
Earthquakes are a result of the process.
Forces at work: movement, tension, shearing, breaking
Forces at work: Compression, bending, breaking
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Forces at work: melting, movement of molten material
(oozing), build-up of gasses under pressure (explosion).
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Steep-sloped rounded peaks
Southern Appalachian Mts., NC
Topographical Units
All the geological processes -- combined with
various atmospheric processes -- give us distinct
landforms within the physiographic regions:
1.
2.
3.
4.
5.
Mountains
Plains
Hills
Plateaus
Coastlines (has a relationship to sea level)
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Folded Appalachians
Rocky Mts., Banff NP, Alberta
in central Pennsylvania
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Fault Block Topography
Basin and Range, Nevada
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Great Plains
North Dakota
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Colorado Plateau
Hill Areas
Foothills, Canadian Rockies,
Alberta
Sand Hills, Nebraska
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Grand Canyon NP, Arizona
Quebec City was built on a hill top
Hills of eastern Tennessee
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Pacific Northwest Volcanic Zone
West Coast Volcanic Zone
Mt. Rainier, WA
Mt. Shasta, CA
Mt. St. Helens, WA
Subduction leads to the
formation of volcanoes.
(1980 eruption)
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Hawaii Volcanoes
Crater Lake, OR
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Lava Flows
The volcanic activity of Hawaii is related to a “hot spot” not a plate boundary.
Kilauea
(active)
Mauna Loa
Lava moving toward the
ocean to create new land
and changing the
Hawaiian coastline.
Hawaii’s largest volcano and world’s tallest
mountain
A black sand beach is created from lava
that is quickly cooled as it hits the ocean
or wave pulverized basalt (hardened
lava) or wave-separated cinders 34
washed ashore.
Diamond 33
Head (extinct)
Rocky Coast
Sandy Coast
Maine
Northeastern U.S.
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Atlantic Coastal Plain
and Barrier Islands
Gulf Coast Plain of Texas
North Carolina
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Southern California Coast
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Central California Coast
Rugged, mountain-fringed coastal area of central California at Big
Sur south of Monterrey.
< Laguna
Beach, CA
^Entrance to San Francisco Bay
^ Torrey Pines beach, San Diego
^ La Jolla, CA
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Pacific Northwest Coastline
Oregon
Northern
California
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Coasts of Alaska
Nome
Juneau
Anchorage
Inland straits of
British Columbia
Mountains rise out of the
sea. There is no coastal
plain and beaches are
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Katmai NP
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NEXT
PHYSICAL
GEOGRAPHY –
Glaciation
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