Download Rocks and The Rock Cycle

ALPHA COLLEGE OF
ENGINEERING AND
TECHNOLOGY
CIVIL A [3RD SEM ]
TOPIC :- TYPES OF ROCK AND ROCK CYCLE
GROUP 1O
ENROLLMENT NO
• DARSHAN R MEHTA
130510106032
• KOMAL N MALVANIYA
130510106030
• HARDIK G MAKWANA
130510106029
Rocks and
The Rock
Cycle
What is a rock?
• A rock is a mixture of such minerals, rock fragments,
volcanic glass, organic matter, or other natural
materials.
• Most rock used for building stone contains one or
more common minerals, called rock-forming
minerals, such as quartz, feldspar, mica, or calcite
• When you look closely, the sparkles you see are
individual crystals of minerals.
How do Rocks form?
• How much time does it take to form a
rock?
– If you squeeze and heat a rock for a
few million years, it can turn into a
new kind of rock.
Continued…
•
Where does the
heat come from?
–
When rocks are
close enough to the
magma to be heated
but not close
enough to be
melted, the rocks
can be changed.
Continued…
• Where does the
pressure come
from?
– Rocks below the
surface are squeezed
by the layers of rock
above them. The
thicker the layers,
the more pressure
there is.
What makes up the earth?
Core
30%
Crust
1%
Crust
Mantle
Core
Mantle
69%
3 Main Rock Types
Igneous
Sedimentary
Metamorphic
THE THREE TYPES OF ROCKS
• Igneous rock is formed from molten
rock that has cooled and hardened.
• Sedimentary rock is formed from
material that has settled into layers and
hardened.
• Metamorphic rock is a rock that has
changed by heat and pressure.
Examples…
Igneous
Metamorphic Sedimentary
Granite
Slate
Sandstone
Obsidian
Marble
Limestone
Pumice
Gneiss
Shale
IGNEOUS ROCKS
• Form by solidification (crystallization) of
melted minerals
• At the surface, LAVA hardens to form
EXTRUSIVE rocks with tiny (FINE-GRAINED)
crystals or GLASSY (no crystal) TEXTURES
• Beneath the surface, MAGMA hardens to form
INTRUSIVE rocks with easily visible (COARSEGRAINED) crystal texture.
Granite
• Light-colored, coarsegrained, no pattern
• Mostly quartz, feldspar,
mica, and hornblende
• Often used for buildings
and monuments
Basalt
• Dark-colored, fine- grained,
extrusive
• Formed where lava erupted
onto surface
• Most widespread igneous
rocks
• Found locally in the
Palisades along west shore
of Hudson River,
Connecticut River valley
Gabbro
• Dark-colored, coarsegrained intrusive
• Similar composition to
basalt—plagioclase
feldspar with some
pyroxene and olivine
Obsidian
• Natural volcanic glass
• Forms when lava cools
very quickly
• Usually dark, but small
pieces may be clear
• Fractures along curved
(conchoidal) surface
• Used as spear and arrow
points, knives
Pumice and other igneous rocks
• Light colored, frothy
(many air spaces)
• Same minerals as in
granite, but finer in
grain size
Igneous
EXTRUSIVE
Forms when lava cools
quickly on the Earths
surface
Forms from molten
rock cooling and
solidifying
INTRUSIVE
Magma cools slowly
over millions of years
deep beneath the
surface
IGNEOUS---Extrusive
Little or NO Crystals!
Lava cools on
the surface so
fast mineral do
not get a
chance to form
Extrusive rocks
can be divided
into two
categories
based on color
Dark colors
black-brownred
Light colors
white-gray-pink
• Basalt
• Obsidian
• Rhyolite
IGNEOUS---Extrusive
Little or NO Crystals!
Lava cools on
the surface so
fast mineral do
not get a
chance to form
Extrusive rocks
can be divided
into two
categories
based on color
Dark colors
black-brownred
Light colors
white-gray-pink
• Basalt
• Obsidian
• Rhyolite
IGNEOUS---Extrusive
Little or NO Crystals!
Lava cools on
the surface so
fast mineral do
not get a
chance to form
Extrusive rocks
can be divided
into two
categories
based on color
Dark colors
black-brownred
Light colors
white-gray-pink
• Basalt
• Obsidian
• Rhyolite
IGNEOUS---Extrusive
Little or NO Crystals!
Lava cools on
the surface so
fast mineral do
not get a
chance to form
Extrusive rocks
can be divided
into two
categories
based on color
Dark colors
black-brownred
Light colors
white-gray-pink
• Basalt
• Obsidian
• Rhyolite
Igneous
EXTRUSIVE
Forms when lava cools
quickly on the Earths
surface
Forms from molten
rock cooling and
solidifying
INTRUSIVE
Magma cools slowly
over millions of years
deep beneath the
surface
IGNEOUS---Intrusive
Large Interlocking Crystals!!!
Magma cools
slowly over
millions of
years…
LARGE CRYSTALS
FORM
Intrusive rocks
can also be
divided into two
categories based
on color
Dark colors blackbrown-green
Light colors
white-gray-pink
• Gabbro
• Granite
3 Main Rock Types
Igneous
Sedimentary
Metamorphic
Sedimentary Rocks
Sedimentary rocks may be made of rock fragments—
sediments—or by chemical reactions. The classification of
sediments is shown below.
How to make a
sedimentary rock
Weathering and
Erosion
Transportation
Compaction and
Cementation
Deposition
Sedimentary
Rock
Sedimentary
Sedimentary rocks are
divided into two categories
Chemical
Clastic
Mineral are dissolved in to the
water…water is evaporated off
and leaves behind chemical
sedimentary rocks
Made from eroded
fragments of other
rocks
Examples are
Halite,
Limestone and
Gypsum
Shale
Microscope grains
of mud cemented
together
Sandstone
Sand grains
cemented together
Conglomerate
Pebble to boulder
size fragments
cemented together
Clastic rocks–made of cemented
sediments—are classified by their grain
sizes.
Non-clastic rocks form by chemical precipitation
(settling out from a solution.) Limestone is made
from calcite, chert from quartz, and halite is rock
salt.
Biologic sedimentary rocks come from
the remains of organic matter.
• The most important of
these is coal. Anthracite
coal results from the
greatest pressure and
releases the most energy
when burned. Other
varieties are bituminous
and lignite. “Petrified”
(permineralized) wood is
another organic rock.
More about sedimentary rocks
• Shale is the most
common sedimentary
rock
• Sedimentary rocks
cover about threequarters of the land
surface
• For more about
sedimentary rocks:
3 Main Rock Types
Igneous
Sedimentary
Metamorphic
Metamorphic rocks form from
HEAT&PRESSURE
Two types of
metamorphism
Contact
Rock surrounding
a magma body get
cooked and
changes due
Regional
Tectonic forces
Metamorphism
occurs over a large
area
Metamorphic Rocks
• Formed by heat and pressure changing
existing rocks
• REGIONAL METAMORPHIC affects a large area
and results from plate tectonics
• CONTACT METAMORPHISM affects rocks on a
local scale, such as “baking” sedimentary
rocks next to magma or lava
“Foliated” rocks contain much mica and other
rocks that produce layering or banding
Gneisses and schists are common in New York City and
Westchester.
Non-foliated metamorphic rocks include marble,
which comes from limestone, and quatzite,
which comes from sandstone
Common Metamorphic Rocks
Parent Rock
Metamorphic Rock
Granite
Gneiss
Shale
Slate
Sandstone
Quartzite
What is the rock cycle?
• To show how rocks slowly change through
time, scientists have created a model called the
rock cycle.
• It illustrates the processes that create and
change rocks.
Here is another version of the Rock Cycle
The Rock Cycle
Rock Cycle
explains
how Rocks and Natural Processes
are related
The
Sedimentary
weathering
Metamorphic
Igneous
The Rock Cycle
Sedimentary
Igneous
Metamorphic
Another Rock Cycle
Mohs Hardness Scale