Transcript Water enters cracks in the rock. When

Formation of a Corrie
Small hollow on the north
facing side of a hillside
Water enters cracks in the
rock. when temperatures fall
below zero the water freezes
and expands putting huge
amounts of pressure on the
surrounding rock. When
temperatures rise again the
water melts releasing the
pressure. This process is
known as freeze-thaw. This
weakens the surrounding rocks.
Snow begins to collect in the hollow, and
soon turns to ice in the falling
temperatures. As snow continues to fall,
the ice overflows out of the hollow to
form a glacier
The glacier freezes onto
the surrounding rocks,
that have been weakened
by freeze-thaw. As the
glacier moves downhill due
to gravity, it tears away
these rocks. This process
is known as Plucking
Huge amounts of rock are
torn away from the hillside,
leaving a huge hollow.
Rocks embedded within the glacier
scrape against the rock surface,
acting like sandpaper, smoothening
the surface. This process is known
as abrasion.
Original profile, before glaciation
After glaciation, a huge
hollow in the hillside, called a
corrie
After glaciation,
a small mound of
moraine is left,
forming a lip
Often meltwater remains in the corrie, known
as a tarn or corrie loch
Formation of a U-Shaped
Valley
Before glaciation, U-Shaped valleys are
V-Shaped river valleys.
Water enters cracks in the rock.
When temperatures fall below zero
the water freezes and expands
putting huge amounts of pressure
on the surrounding rock. When
temperatures rise again the water
melts releasing the pressure. This
process is known as freeze-thaw.
This weakens the surrounding
rocks.
Snow and ice begin to move
through the valley floor as a
glacier.
The glacier freezes onto the
surrounding rocks, that
have been weakened by
freeze-thaw. As the glacier
moves downhill due to
gravity, it tears away these
rocks. This process is
known as Plucking
Huge amounts of rock are
torn away from the valley
sides and base, leaving
very steep sides and a flat
base.
Rocks embedded within the glacier
scrape against the rock surface, acting
like sandpaper, smoothening the
surface. This process is known as
abrasion.
Original profile, before glaciation
After glaciation, a UShaped valley has been
formed, with steep side
walls and a flat base.
Name 3 similarities between the
formation of a Corrie and the
formation of a U-Shaped Valley
• Freeze – Thaw Action
• Plucking
• Abrasion
Before Glaciation
During Glaciation
After Glaciation
Task 1:
Using the information that you have just heard and your
notes, answer the following question;
Select one feature of glacial erosion
and explain the processes involved in the
formation of this feature.
Annotated diagrams may be used.
4 marks