1. 3 types of rocks
Igneous rocks - produced when magma from the
mantle cools and solidifies.
Sedimentary rocks - formed by burial,
compression, and chemical modification of
deposited weathered rock debris or sediments at
the earth's surface.
Metamorphic rocks - created when existing rock is
chemically or physically modified by intense heat
or pressure.
2. •Where rocks come from.
•Importance of rocks.
•Types of rocks.
•Formation of rocks.
3. The crust is like a thin
skin, with an average
thickness of about 30
kilometres.
Beneath the crust is the
mantle—about 3000 km
thick. It consists of solid
rock, but under certain
conditions it can bend
and flow like a thick
paste
4. The crust and the top of
the mantle is called the
lithosphere which means
‘rocky sphere’.
Below the lithosphere the
rocks are under immense
pressure. They are very
hot, and in parts molten.
This molten rock is called
magma. It also contains
dissolved gases.
5. A rock is a solid substance that occurs naturally
because of the effects of three basic geological
processes;
Magma Solidification;
Sedimentation of weathered rock debris;
Metamorphism.
6. 3 types of rock formations
Igneous rocks - produced when magma from the
mantle cools and solidifies.
Sedimentary rocks - formed by burial,
compression, and chemical modification of
deposited weathered rock debris or sediments at
the earth's surface.
Metamorphic rocks - created when existing rock is
chemically or physically modified by intense heat
or pressure.
7.
8. Rocks can tell us many stories;
Where the rock was formed;
The general water depth (if marine or fresh water)
The relative age of the rock (using fossils)
Or it’s absolute age (if radioactive materials are
present)
Its original position and orientation on the surface
of the earth
9. Igneous rocks – 2 types
Intrusive (Plutonic) rock the magma has cooled and
solidified within the earths crust
Extrusive (Volcanic) rock the magma cools and
solidifies on the earth’s surface.
10. Rate of cooling & temperature changes determine the
texture & degree of crystallization
The composition of the magma will determine the
composition of the igneous rock
11. Volcanoes form through weak spots in the earth’s
crust.
These may crack and allow magma to flow from
the mantle to the surface.
When this happens a volcano forms.
The pressure inside the Earth pushes the magma
upwards. Sometimes the molten rock oozes out
steadily. At other times it blasts out with incredible
force.
Usually have no or small crystals
13. The longer Magma has to cool down the
larger the crystals will form in the rock.
The size of the crystals demonstrates where
it came from
14. What rock can float on water?
C)Aerolite
D)Pumice
E)Chalk
F)Eolianite
15. Pumice is a type of lava full of gas bubbles. It can
be as light as Styrofoam, or nearly as dense as
normal rock.
Aerolite is an old name for meteorites, and
Eolianite is any rock type that is made of
windblown sediment. Chalk is a lightweight rock,
but not that light.
16.
17. There are sometimes weak spots in the Earth’s
crust that may crack and allow the magma to flow
from the mantle to the surface. When this happens
a volcano forms.
The pressure inside the Earth pushes the magma
upwards. Sometimes the molten rock oozes out
steadily. At other times it blasts out with incredible
force.
Above ground = from lava (extrusive igneous
rock)
Usually have SMALL or NO crystals
(they cooled too quickly)
18. Basalt Granite
1. Dark color 1. Light color
2. High specific gravity 2. Low specific gravity
3. Fine grained
3. Coarse grained
4. Forms at the surface,
principally in the ocean basins, 4. Forms on the continents
but also in isolated "hot spots" deep underground
on the continents.
19.
20. Why do we see
intrusive igneous
rocks at the
surface of the
earth?
21. Once a rock is formed, does it stay the
same rock forever?
22. 3 types of rocks
Igneous rocks - produced when magma from the
mantle cools and solidifies.
Sedimentary rocks - formed by burial,
compression, and chemical modification of
deposited weathered rock debris or sediments at
the earth's surface.
Metamorphic rocks - created when existing rock is
chemically or physically modified by intense heat
or pressure.
23. How many main types of Rocks are there?
Igneous rocks are formed sediments?
Rocks can break down from rain?
The Majority of rocks found on the surface of the
planet are Metamorphic rocks.
2 Types of Igneous Rocks are?
How are extrusive (plutonic) rocks exposed?
24. Igneous rocks – 2 types
Intrusive (Plutonic) rock the magma has cooled and
solidified within the earths crust
Extrusive (Volcanic) rock the magma cools and
solidifies on the earth’s surface.
25.
26. Do you know the Rock Cycle?
How are sedimentary rocks formed?
What can sedimentary rock tell us?
How are Metamorphic rock formed?
What change occurs to the mineral grains when a
Sedimentary or Igneous rock changes to
metamorphic rock?
27. ormed from sediments
rock fragments, mineral grains,
animal & plant remains) that
are pressed or cemented
together or when sediments
precipitate out of a solution.
28. hese sediments are moved by wind, water, ice
or gravity.
edimentary rocks represent 7% of the Earth’s
crust, but they cover 70% of the Earth’s
surface.
edimentary rocks are
29. As sedimentary rocks
are deposited, they
form horizontal layers
Scientists know that
the layers on top (and
the fossils in the top
layer) are YOUNGER
than the fossils in
lower layers.
30. ater or wind breaks down and deposits sediment
(erosion & deposition)
33. Clastic (also called Detrial)—made of
broken pieces of other rocks
34. Organic—remains of plants and animals
are deposited in thick layers
Examples
Fossil rich limestone is made from the
shells of ocean animals; used to make
chalk
35. Chemical—minerals dissolved in
lakes, seas, or underground
water
Mineral crystals are made as the shallow water that has
flooded the bottom of Death Valley evaporates.
Click on image for full size (66K JPG)
Courtesy of Martin Miller, University of Oregon
36. Examples
Limestone
made when
calcite
mineral
precipitates
from sea
water
Rock Salt—
made from
evaporation
of sea
waters
37. Rocks that have changed due to intense
temperature and pressure
Igneous, sedimentary and other
metamorphic rocks can change to become
metamorphic rocks
Meta” means “change” and
morphosis means “form”
in Greek
38. Places that are covered
miles thick with other rock
causing pressure
Near colliding plates (near
mountain ranges)
Where magma intrudes
relatively cool rock
When hot water intrudes
rock
Where a meteorite strikes
Earth (rare)
Where lightning bolts strike
rocks (rare)
39. Pressure from overlying rock layers
High heat, but not enough to melt the rock
Rocks may be flattened or bent or atoms may be
exchanged to form new minerals.
40. The minerals grains in rocks subjected to extreme pressure often
rearrange themselves in a parallel fashion, creating a foliated texture
(Image A - before metamorphism; Image B - after metamorphism).
41. Foliated—mineral grains are flattened and
line up in parallel bands
Example: gneiss formed from
rearrangement of minerals in granite into
bands
42. Non-Foliated—No bands are formed
Example: marble formed from limestone
43.
44. Write down what type of rock you think it
might be.
Based on what reason have you suggested what
type of rock it is? Hint: Explain what features
you observe for each rock
Draw a simple picture of each rock
No. Type of rock Rational Diagram
1 Sediment Has a grain appearance –
looks like compressed
grains
2 Igneous - Plutonic Has medium sized
crystals. Coarse grained
45. • No set path a rock takes to become
another kind of rock
48. IGNEOUS
1
Weathering, Erosion,
Compaction, Recrystallization
Cementation
Melting,
Solidification Melting,
Solidification
Recrystallization
S E D 2M E N T A
I 3
M E TA M O R P
RY H IC
Weathering, Erosion,
Compaction,
Cementation
