PHYSICAL GEOLOGY AND THE ENVIRONMENT
(2ND CANADIAN EDITION)
Chapter 20: Geological History of Canada
Chapter Summary:
Canada's lengthy geologic history began more than 4 billion years ago, when the North American
craton began to form. Many separate land masses were fused together by plate tectonics
processes over several billion years to create a craton consisting of geologically distinct
provinces. Deformed rocks of the craton identify areas where land masses were sutured together,
and are termed orogens. These ancient rocks of North America record repeated episodes of
supercontinent formation and breakup and are exposed on the Canadian Shield.
The outermost margins of the North American craton have been buried by younger cover rocks.
These sedimentary rocks were deposited in extensive shallow seas (intracratonic and foreland
basins) that covered parts of the craton when it was depressed by the weight of developing
mountain ranges. Most of Atlantic Canada originated as parts of other continents that were
accreted onto the eastern seaboard of North America through repeated opening and closing of
ancestral forms of the Atlantic Ocean. Western Canada also formed by the accretion of many
former land masses (terranes) onto North America as it slowly drifted westward after the opening
of the modern Atlantic Ocean. The Canadian Rockies record compression caused by these
collisional events on the western margin. Canadian sedimentary rocks contain a rich fossil record
including some of the earliest animal fossils (Ediacaran fauna) and numerous species of dinosaur
that roamed the swamps around inland seas.
The most recent events in Canada's geologic history involve climate changes that saw the gradual
cooling of warm climates, and the repeated growth and decay of enormous ice sheets that
covered almost all of Canada. Many of the landscapes most familiar to Canadians are the product
of glacial processes active during the past 2 million years. Glacial erosion is responsible for the
formation of steep-walled glacial troughs and fjords in mountainous areas, streamlined landforms
of the Canadian Shield, and excavation of the Great Slave, Great Bear, and Great Lakes basins.
Glacial depositional features include drumlin fields, hummocky moraine, and extensive plains
underlain by till and outwash that host productive aquifers. Canada's geological history continues
to evolve as landslides alter the form of mountains and valleys, quickclays fail, deltas develop,
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PHYSICAL GEOLOGY AND THE ENVIRONMENT
(2ND CANADIAN EDITION)
and coastal erosion continues.
Questions:
1. The mountain belt that forms the western part of North America is called the: (Page 556)
A. Appalachian Mountains
B. Himalayas
C. Canadian Cordillera
D. Ouachita Mountains
2. The North American craton: (Page 541)
A. is the portion of a continent with the highest mountains
B. is the geologically stable portion of the continent
C. is the youngest portion of the continent
D. none of these
3. The Canadian Shield is: (Page 541)
A. a defensive system along the southern border
B. a glacier
C. the exposed portion of the craton
D. the unexposed portion of the craton
4. Rodinia is: (Page 544-547)
A. the name of a supercontinent
B. a province
C. a terrane
D. a type of rock
5. The large sedimentary basin that existed during the Carboniferous was called the: (Page 544-
547)
A. Atlantic Basin
B. Prairie Basin
C. Maritimes Basin
D. Pacific Basin
6. Mountain peaks that protruded through ice sheets are called: (Page 563-564)
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