Download Science 7: Unit E – Topic 7 Notes: Mountains

Science 7: Unit E – Topic 7 Notes: Mountains
How Are Mountains Formed?
 Mountain building takes millions of years.
 Most mountain ranges are formed from the movement
of _________ _______, usually in a __________ zone
from the compression of the Earth’s crust.
 A large mountain range is called a ___________. The
Canadian Rockies are part of the Western Cordillera
which also includes the American Rockies and the
Alaskan Rockies.
Faulting and Folding
 ______________ rock can be faulted or folded into
mountains:
 __________ – The breaking of sedimentary rock as
parts are pushed up over other rock.
 __________ – The bending, but not breaking of
sedimentary rock as the crust is compressed and forced
upwards.
Syncline and Anticline
 Synclines and anticlines are formed through the
________ process.
 _________ – the downward or bottom part of the fold.
 _____________ – The upward or top part of the fold.
Thrust Faulting and Fault Block Mountains
 ______ __________ – Sedimentary rock is broken into
separate sheets or ‘slabs’ These sheets can then be
pushed over or under other sheets.
 ______ _______ ____________ – Compression forces
form the slabs and the continued pushing can cause the
older rock to slide on top of the newer rock.
 __________ ______ – The bottom layer of the
mountain which the other layers slide on top of.
Complex Mountains
 When an _______ plate meets a ____________ plate,
it subducts under the continental plate.
 This compression gives off heat and pressure which
help to form mountains.
 ________ ________ – mountains formed from melting
and compression when an oceanic plate meets a
continental plate.
 The Rocky Mountains formed 500 million years ago
when the Pacific plate subducted under the North
America Plate and the N. America Plate edge began to
______ _____.
Young and Old Mountain Ranges
 Young Mountain Ranges – are jagged and rough. They
have not been polished smooth by weathering. The
Himalayas and Rockies are ‘young’ mountain ranges.
Young Mountain ranges are growing higher every year
due to compression.
 Old Mountain Ranges – smooth and rounded peaks.
They are polished smooth and are growing smaller
every year due to the processes of weathering and
erosion.