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