Transcript Gifts from the Past Procedure

March 18:
QoD: Which books do you think
are older?
Today’s Outline: March 18
 New and improved Frayer
 Stratigraphy
 Fossils
The Grand Canyon: U.S.
Moab, Utah
Grand Canyon, Arizona
Stratigraphy –
The Study of
Rock Layers
Grand Canyon
Gifts from the Past Procedure
pg. 284. #2 a-c: Follow the
instructions with a partner. Label
your drawing.
“Relative” age
Gifts from the Past Procedure
3. Read and record your answers
in your science notebook. Make
sure to answer both a and b
Fossils:
- any preserved remains or
traces of a once-living thing
-Rarely are the soft bodied
parts preserved
How Most Fossils are Formed
1. An organism dies: must be quickly
covered by sediments.
2. Sediments build up over the years.
3. Once buried, many dead organisms
may quickly decay, leaving a “mold” in
the rock. The mold may fill in with
minerals forming a cast; OR,
4. Permineralization occurs (organic
tissues replaced by minerals in
groundwater).
Fossils:
Examples of the formation process just
described: Casts, petrified bones and
wood, casts and molds of organisms
Also can have: Organisms wholly
preserved in amber, volcanic ash, ice,
peat bogs, tar pits, etc.
Finally, can have: Imprints left behind
(footprints, worm tracks etc.)
PETRIFIED BONE
1. Fossils: examples
WASP IN
AMBER
IMPRINT
PETRIFIED LOG
SLOTH IN
TAR PIT
Fossil hunting in Washington
Bellingham
Republic
Harts Pass
(Blue Lake Rhino)
Saddle Mountain
Blue Lake Rhino
Fossil Evidence
- quality of fossils varies
- fossil skeletons are not
always complete
- fossil record is not complete
Relative Dating:
- Upper layers of rock are
younger than lower layers
(almost always, more later
on this…)
Relative Dating
using Index Fossils
Gifts from the Past procedure
5.
6.
7.
8.
9.
Use the provided samples and choose
one fossil to study, draw it in your
notebook.
Look at your group of sample fossils
and the fossils in Figure 6.9 and answer
6. a-c in your notebook.
Write down what you notice about the
fossils and where they are in the rock
layers.
Answer #8 a-c
Take notes on the following slides
Answers to 8.
a.
b.
c.
The coral fossil is older than the dinosaur
bone because it is located in a lower layer
than the dinosaur bone. The lower rocks are
older than rocks closer to the surface.
Brachiopod, ammonite, fish, coral and shark
tooth are from a marine environment.
Crocodile is from swamp. Dinosaur from
terrestrial. Petrified leaf and wood from
forested area. Horse from grassland.
The environment has changed over time from
marine to terrestrial.
Law of Superposition
Layers are arranged in a
time sequence, with the
oldest on the bottom and the
youngest on the top,
UNLESS later processes
disturb this arrangement.
Quick write
Turn to the next page in your
notebook and write down in your
own words the Law of
Superposition
Check with your notes-discuss with
your partner how close you were to
the definition-would you change
anything in your answer
Radioactive Dating
Technique used by scientists
to determine the age of
fossils relative to other
fossils in different layers of
rock.
Microraptor gui
This “missing link” was recently
discovered in China in 2006.
Sinornithosaurus
Repenomamus
giganticus
This “missing link” was recently
discovered in China in 2005.
Assignment:
Answer the Reflect and
Connect questions
2 – 4, p. 288
Answers to Reflect and Connect
2. If a fossil is found below another one then it
is probably older because the layer was
deposited first.
3. Fossils of plants and animals in a series of
rocks can show that environments have
changed because the types of organisms have
changed. Some organisms might have existed
for a short period of time and can be used to
date certain rocks (Index fossils)
4. Relative age provides the order that things
occurred in but does not provide a date.
The
End
Gifts in the Past Procedure
4. A. Watch the fossil demonstration
on fossil deposition first, then
read the paragraphs on pg. 285.
B. Turn to your elbow partner and
ask the following questions:
What is a fossil?
How do you think fossils are formed?
c. Class discussion on how fossils
are formed, take notes