Download **CONVECTION CURRENTS** take place in the slow moving

CONVECTION CURRENTS and the Movement of the Earth’s Crust
HEAT TRANSFER – Heat is passed from HOT/Warmer regions, to COLD/Cooler regions.
This happens in 3 ways…
1.
CONDUCTION – when heat is transferred by DIRECT CONTACT of matter particles (touching)
2.
CONVECTION – when heat is transferred by the MOVEMENT of a fluid (liquid or gas).
3. RADIATION – when heat is transferred through EMPTY SPACE (in the form of electromagnetic waves)
RECALL……
LITHOSPHERE = The SOLID, RIGID outer portion of the Earth that is composed of the CRUST and
UPPERMOST MANTLE.
ASTHENOSPHERE = The HOT, SOFT, WEAK, SLOW MOVING portion of the UPPER MANTLE.

Lithosphere
FLOATS
on top of the Asthenosphere
**CONVECTION CURRENTS** take place
in the slow moving ASTHENOSPHERE

So, the Lithosphere

CONVECTION CURRENTS are the circular flow or movement within a
liquid or gas, due to a variation in
DENSITY caused by
TEMPERATURE differences.
o
DENSITY


FLOATS
on these
CURRENTS
.
is the ‘amount of matter’ (mass) in a given ‘space’ (volume).
How do density and floating relate?
 Relative to Surroundings: More dense things SINK and Less dense things FLOAT
When a liquid or gas is
HEATED
, it becomes
LESS
dense.
- It becomes LESS dense because when it is heated, the substance EXPANDS (spreads out)

When a liquid or gas is
COOLED
, it becomes
MORE
- This is because when an liquid or gas is cooled, the substance
dense.
CONTRACTS (squeezes down) .
CONVECTION CURRENTS and the Movement of the Earth’s Crust
LITHOSPHERE
4. Soft Rock COOLS
because it is FAR from
the CORE.
5. COOL Rock SINKS in
the Asthenosphere,
because it is
MORE DENSE.
3. Soft Rock reaches Lithosphere
and SPREADS OUT.
2. HOT, Soft Rock in the
Asthenosphere RISES
because it is
LESS DENSE.
4. Soft Rock COOLS
because it is FAR from
the CORE.
5. COOL Rock SINKS in
the Asthenosphere,
because it is
MORE DENSE.
1. SOFT ROCK deep in the
Asthenosphere is HEATED by the
EARTH’s INTERIOR.
6. Cool Rock sinks down
in the Asthenosphere
and REPEATS
6. Cool Rock sinks down
in the Asthenosphere
and REPEATS