Transcript Notes-3.3.ppsx

3.3 Notes
Sedimentary Rocks
Think About
• What do you think would settle to the
bottom of a body of water faster, rocks
or sand?
Rock Particles
•MOST sedimentary rock
forms from sediment
getting pressed
together and
cemented into rock.
Rock Particles
•Sedimentary rock takes its name from
the word sediment, which means
“something that settles.”
Rock Particles
•Sediments are loose
materials that settle
out of water or air.
Rock Particles
•Pieces of plant and
animal remains can
make up sediments
in addition to loose
rocks and minerals.
Rock Particles
•Sediments can
range in size
from boulders to
sand.
Rock Particles
• Rain washes away tiny
rock pieces as it flows
downhill.
• The water carries these
particles to rivers which
eventually empty into
lakes or oceans.
Rock Particles
•Wind can also pick up sand and rock
dust and carry them to distant
places.
Rock Particles
• As water or wind deposits
sediments in layers, the layers
eventually get buried by more
layers.
• The layers on top press down
on the layers underneath.
Rock Particles
• Sometimes this pressure is
enough to turn the layers into
rock.
• Other times, minerals also
crystallize between the layers
and cement them together.
Rock Particles
•Sedimentary rock formed from
loose rock particles is called
detrital sedimentary rock.
Rock Particles
• If sand grains on a
beach become
cemented together,
they form a
sedimentary rock
called sandstone.
Plants or Shells
•Sedimentary rocks can also be
produced from shells or plant
remains (fossils).
Plants or Shells
•If you look at a piece of
coal through a
magnifying glass, you
may see shapes of wood
or leaves.
Plants or Shells
•Coal is made up of remains of plants.
•That is why coal is called a “fossil fuel.”
•The coal we use today started forming
millions of years ago.
Plants or Shells
• Limestone is made of carbonate minerals such
as calcite, found in organisms with shells.
Plants or Shells
• When shelled organisms
die, their shells settle
on the ocean floor as
sediment.
• Eventually, this
sediment is formed into
limestone.
Plants or Shells
•Sedimentary rock formed from
fossils is called organic
sedimentary rock.
Dissolved Minerals Re-Form from Water
• Some sedimentary rocks are made up of
minerals that crystallized as water
dried up.
Dissolved Minerals Re-Form from Water
• As water moves through
limestone, some of the
rock dissolves.
• This can eventually form
huge open spaces
(caves) in the rock.
Dissolved Minerals Re-Form from Water
• As the water flows and
drips through a cave,
some of it evaporates,
making many odd and
beautiful shapes.
Dissolved Minerals Re-Form from Water
• Sometimes minerals
crystallize along the edge of
lakes and oceans when the
water evaporates.
• This is how salt and gypsum
are both formed.
Dissolved Minerals Re-Form from Water
•Sedimentary rock formed by the
evaporation of water is called
chemical sedimentary rock.
Sedimentary Rocks Show the Action of Wind
and Water
• Sedimentary rocks are
laid down in layers,
with the oldest layers
on the bottom.
Sedimentary Rocks Show the Action of Wind
and Water
• Geologists can study
these layers to know
what Earth was like in
the past.
Sedimentary Rocks Show the Action of Wind
and Water
• The sediments also tell
geologists what wind and
water erosion were like
in the past.
Sedimentary Rocks Show the Action of Wind
and Water
•A rock layer with large particles on
the bottom and small particles on
the top indicate that the water
carrying the sediment was slowing
down.
Sedimentary Rocks Show the Action of Wind
and Water
•This kind of rock layer is often
created by a flood.
Sedimentary Rocks Show the Action of Wind
and Water
• Sedimentary rocks can
also show the directions in
which long ago wind or
water currents were
moving when sediments
settled from them.
Sedimentary Rocks Show the Action of Wind
and Water
• Rocks made of clay or silt
with cracks indicate they
were formed during a wet
period followed by a dry
period.
Review
1.Pieces of rock can settle from water
and get cemented into
A.Metamorphic rock
B.Sedimentary rock
C.Igneous rock
D.Extrusive rock
Review
2. Rock salt is an example of a sedimentary
rock that develops from dissolved minerals as
A.Water evaporates
B.Magma cools
C.Sediments break down
D.Sand settles in water
Review
3. When hiking outdoors you notice an object and pick it
up. You observe the following characteristics: the object is
black in color, has a rough texture, dull in luster, and
contains organic matter. What is the object you are
holding?
A. Obsidian
B. Quartz
C. Coal
D. Magnetite