Transcript Lesson 5 Weathering and the rock cycle

Do now!
Can you stick the freeze-thaw
weathering paragraph into
your book?
Last lesson
• Weathering of rocks – Freeze-thaw
weathering
Freeze-thaw weathering
In high mountainous areas, rain water can seep
into the small cracks in a rock. At night-time the
air gets very cold and the water freezes. When
water freezes it expands making the crack wider.
During the day the water melts and falls deeper
into the now larger crack. This happens
repeatedly, the crack gets bigger and bigger, and
eventually a piece of rock is broken away from the
mountain.
Educational freedom fighters!
This class is being held hostage by
educational freedom fighters (just outside).
We have to decide as a class which is the
most important word in the paragraph. If we
get it wrong, they are going to shoot us!!!!!
Today’s lesson
• Chemical and physical weathering
• Transport
• The Rock Cycle
Can you gather around Mr Porter?
Chemical
weathering
Rain is
slightly acidic
as it contains
substances
dissolved from
the air. It can
react with
rock,
dissolving it.
Chemical weathering
Some rocks are dissolved more by acid rain
than others
Limestone
“pavement”
Physical weathering
Rocks can be weathered by physical
changes
Physical weathering
When rocks are hot they expand, and when
they cool they contract. Repeated changes
cause the rock to crack, often causing rock
to peel off.
Sometimes
called
“onion-skin
weathering”
You now know all about
freeze-thaw weathering
Physical weathering
Freeze-thaw weathering is another example
Transport
Rock falls to the
bottom of rock
faces and may be
transported away
by fast moving
streams.
Abrasion
The rocks in the stream bed rub against
each other and wear away. This is abrasion.
Sediment
The bits of rock in the stream bed are called
sediment.
Deposit
Smaller rock fragments are carried further
than large ones, eventually being deposited
on the bottom in slow water.
The Rock Cycle
Can you read page 100
very carefully?
The Rock Cycle
The Rock Cycle
The Rock Cycle
Can you draw your own
copy of the Rock
Cycle?
NO PEAKING!!!