geography of the united states & canada€¦ · north america, (cascades & sierra...
TRANSCRIPT
GEOGRAPHY
OF THE
UNITED STATES
& CANADA
By Brett Lucas
PHYSICAL GEOGRAPHY
Outline
The North American landscape
The effects of glaciation
Hydrography
Climate
Vegetation and ecosystems
Canadian Shield
Oldest exposed rock
on earth
Glaciers removed
much sediment
Many lakes and
streams
Bare rock
Gentle slopes
Canadian Shield
Appalachians, Interior Uplands,
Piedmont
Once a principal
mountain range in NA
Taller than Everest?
570 M years old
Stopped growing 200
M years ago
Narrow valleys and
steep hillsides in
places.
Appalachian Mtns. North Carolina
Appalachians, Interior Uplands,
Piedmont
Appalachians, Interior Uplands,
Piedmont
Gulf-Atlantic Coastal Plain
Cape Cod to Texas
Erosion from
Appalachians, Interior
Lowlands, Great Plains
<70M years old
No true coastline
Marshes and swamps
Gentle slope
Sanibel Island, Florida
Interior Lowlands & Great Plains
Sediment washed out
from the Rockies to the
west, and Appalachians
to the east.
Gentle grade, 1 mile
high in west (Denver) to
near seal level
Few distant features
Lakes occur in glaciated
areas. Western Saskatchewan
Rocky Mountains
Mix of different rock types and causes
Stretches from Alaska to New Mexico, with peaks over 14,000 feet in height.
Significant gap only in Wyoming.
70M years old.
Steep terrain, aided by mountain glaciers.
Longs Peak, Rocky Mountain
National Park, Colorado
Intermontane Region
Varied geologic history
Often referred to as
“Basin & Range,”
especially in the SW
and Nevada.
Uplifted sedimentary
rock (plateaus) undercut
by rivers (basins)
Nevada: internally
drained
Typical basin and range topography
Pacific Coast
Last remaining
volcanoes
Tallest mountains in
North America,
(Cascades & Sierra
Nevada’s).
Active subduction &
faulting
Seismic activity
Volcanoes
Earthquakes
Earthquakes
Continental Glaciation
Ice sheets
Covered much of Canada and northern US through periods of the last 1-2 M years
Once 3-km thick over Hudson Bay
Has mostly receded to the Canadian Archipelago and a few sheets in the Canadian Rockies and British Columbia
Alpine Glaciation
Mountain glaciers
Much more limited
extent than during
past
Still occur as far
south as Colorado
and Sierra Nevada
Most extensive in
Alaska and Yukon
Athabasca Glacier, Alberta
Effects of Glaciation
Reshaped land
dramatically.
Carved out some
significant water bodies
Generally smoothed
landscape
Sheared off higher
terrain.
Filled in lower terrain
Landscape still evolving.
Glacial striations, Lac Blanchet, Canada.
(Source: Natural Resources Canada -
Terrain Sciences Division - Canadian
Landscapes).
Hydrography
Natural lakes generally only in glaciated areas
Almost all lakes elsewhere are artificial
Rivers generally carry much greater volumes in east
and north Pacific coast
Meandering rivers with gentle slope
Entrenched rivers with steeper slope or uplifted
land
Drainage Basins – United States
Drainage Basins – Canada
Climate of North America
What is climate?
How is climate different from weather ?
What factors influence the climate of a location?
Precipitation & Rain Shadow
Precipitation & Rain Shadow
Types of Forests
Coniferous (evergreen)
Canada, Pacific Coast, some places in the southern
US
Deciduous
Eastern US, southeastern Canada
United States Forest Cover
Grasslands
Insufficient rainfall for
trees.
Taller grasses with
greater rainfall
Central US and
Canada, Tundra
Shrublands
Too dry for grasslands,
especially summer.
California, deserts,
interior west