Transcript Geologic Eras 4

Utah’s Geology
& the History of
the Earth
Utah’s Geologic Past:
Proterozoic to
Mesozoic
Take out your study
guide and notes.
Bell
Silently read the
document “How
Fossils Are Made” on
the last (pink) page of
your green folders.
 Read carefully then
answer questions on the
back of the pink paper.
Activity
Answer these
questions on the
next page of your
Geo note packet.
• Now answer the
questions from the
back of the page you
just read. Put the
answers in your Geo
history note packet.
• Good readers look
back at what they
have read if they are
unsure about what to
answer!
After the
reading…
• Check your
understanding.
Today we will be learning
about…
 Social Studies Objective –  Language Objective –
We will understand that
the Earth, and Utah, has
changed a lot in the past.
We will be able to describe
how fossils are formed.
We will be able to
summarize what a past
era was like in writing.
 Behavior Objective – Work Ethic: Are you staying
on task?
Posters
• As long as your
poster has all the
information it
should, you can
design it how you
want.
• For those of us who
like a little
guidance, here is
what your first
poster might look
like…
Percentage of Time:
Deep time demonstration
Let’s see how much of Earth’s geologic history was taken
up by this era.
If we converted the whole history of the earth into a timeline
5 feet long, how much of line would the Paleozoic Era take
up. (Math!!! 60 inches x 17.5% = _______ inches)
• Hadean 17.5%
• Archaen 28.5%
• Proterozoic 42%
• Paleozoic 7%
• Mesozoic 4%
• Cenozoic 1%
Paleozoic Era
• We will read a short
description of the
era, then watch a
short video about
it, and finally, talk
about what
happened in Utah at
this time.
Fossil Hunting in Utah
Let’s work
• Let’s fill out the
first poster
together.
• What do we
remember
about the
Paleozoic time?
Check
Your Work
**This part of the PowerPoint was created by Mrs. Schreck-Leishman, MLMS
What is a fossil?
•
A fossil is the preserved remains of a onceliving organism.
What do fossils tell us?
•
Fossils give clues about organisms that lived
long ago. They help to show that evolution
has occurred.
•
They also provide evidence about how
Earth’s surface has changed over time.
•
Fossils help scientists understand what past
environments may have been like.
HOW IS A FOSSIL FORMED?
1. Sediment
2. Layers
3. Movement
4. Erosion
An animal is buried by
sediment, such as
volcanic ash or silt,
shortly after it dies. Its
bones are protected
from rotting by the
layer of sediment.
More sediment layers
accumulate above the
animal’s remains, and
minerals, such as silica
(a compound of silicon
and oxygen), slowly
replace the calcium
phosphate in
the bones.
Movement of tectonic
plates, or giant rock
slabs that make up
Earth’s surface, lifts
up the sediments and
pushes the fossil
closer to the surface.
Erosion from rain,
rivers, and wind wears
away the remaining
rock layers. Eventually,
erosion or people
digging for fossils will
expose the preserved
remains.
FIVE MAIN TYPES OF FOSSILS
Petrified
Fossils
Molds and
Casts
Trace
Fossils
Carbon
Films
Preserved
Remains
PETRIFIED FOSSILS
• The word “petrified” means
“turning into stone.”
• Petrified fossils form when
minerals replace all or part
of an organism.
PETRIFIED FOSSIL
The Field Museum in Chicago
displays a fossil of a
Tyrannosaurus rex.
• Water is full of dissolved
minerals. It seeps through
the layers of sediment to
reach the dead organism.
When the water evaporates,
only the hardened minerals
are left behind.
MOLDS AND CASTS
• A mold forms when hard parts of an
organism are buried in sediment,
such as sand, silt, or clay.
MOLD FOSSIL
This mold, or imprint, is of
an extinct mollusk called
an ammonite.
• The hard parts completely dissolve
over time, leaving behind a hollow
area with the organism’s shape.
• A cast forms as the result of a mold.
• Water with dissolved minerals and
sediment fills the mold’s empty
spaces.
CAST FOSSIL
This ammonite cast was
discovered in the United
Kingdom.
• Minerals and sediment that are left
in the mold make a cast.
• A cast is the opposite of its mold.
CARBON FILMS
• All living things contain an
element called carbon.
• When an organism dies
and is buried in sediment,
the materials that make up
the organism break down.
FERN FOSSIL
This carbon-film fossil of a
fern is more than
300 million years old.
• Eventually, only carbon
remains.
• The thin layer of carbon
left behind can show an
organism’s delicate parts,
like leaves on a plant.
TRACE FOSSILS
• Trace fossils show the
activities of organisms.
• An animal makes a footprint
when it steps in sand or mud.
FANCY FOOTWORK
This dinosaur footprint was
found in Namibia, Africa.
• Over time the footprint is
buried in layers of sediment.
Then, the sediment becomes
solid rock.
PRESERVED REMAINS
Some organisms get preserved in or close to their
original states. Here are some ways that can happen.
Amber
Tar
Ice
An organism,
such as an insect,
is trapped in a
tree’s sticky resin
and dies. More
resin covers it,
sealing the insect
inside. It hardens
into amber.
An organism,
such as a
mammoth, is
trapped in a tar pit
and dies. The tar
soaks into its
bones and stops
the bones from
decaying.
An organism,
such as a woolly
mammoth, dies in
a very cold region.
Its body is frozen
in ice, which
preserves the
organism—even
its hair!
Earth Conditions
During Dinosaur Times
Lush Tropical
Environment
•Large bodies of water
•Humid & rains a lot
• Variety of plant life
•Lots of animal life
Earth Conditions Now
– Same Location
Arid Sagebrush
Desert
•Little water – DRY
•Rains very little
• Few trees or plants
•Minimal animal life
Green River Stone Quarry
Green River Stone Quarry
Green River Stone Quarry
Green River Stone Quarry
Green River Stone Quarry
Green River Stone Laboratory
Green River Stone Laboratory
Green River Stone Laboratory
Green River Stone Company
Green River Stone Company
Green River Stone Company
Green River Stone Company
Green River Stone Company
How the Earth Was Made
• We are going to watch
some short clips from
the series “How the
Earth Was Made”.
• Compare what they
say with what you
learned about each
time period.
• If necessary, add
some more details to
your descriptions.
If you are not paying attention, there
will be a quiz at the end of the clips.