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Unit 2 Historical Geology Ch 12-13

Week 1 Notes:

Vocabulary for week 1:

  1. uniformitarianism
  2. relative dating
  3. law of super position
  4. principle of original horizontality
  5. principle of cross cutting relationships
  6. unconformity
  7. correlation

Week 1 Objectives:

Investigate and compare methods used to determine geologic time (relative dating, fossil record, absolute dating) p. 336-352

What are three main ideas of geoscience? p. 336

  1. the rock record provides evidence of geologic events and life forms of the past
  2. processes observed on Earth in the present also acted in the past
  3. Earth is very old and has changed over time

What are the key principles of relative dating?  p. 337

  1. law of superposition- in undisturbed layers of sedimentary rock, the o rock, older layers are below more recent layers.
  2. principle of original horizontality – layers of sediments are deposited in horizontal layers
  3. principle of cross-cutting relationships – a rock layer is older than a fault or igneous intrusion that cuts through it.

Page 339 of our text

 

 

 

Questions:

1.  Is Dyke A older than or younger than the sill?  How do you know?

2.  Is Fault A older than or younger than the sandstone?  The conglomerate?  Explain.

3.  Using the illustration, list the following in order from oldest to youngest using the letters.

A.  Dyke B         C.  Sandstone       E.  Shale

B.  Fault B          D.  Batholith       F. Conglomerate

_______ –>_______ –>_______ –>_______ –>_______ –>_______

 

How do geologists interpret the rock record?  p. 339

  1. The study of inclusions and unconformities
  2. Correlation of rock layers in different locations

3 Types of Unconformities

1.  Disconformities

Click here for an animation of a disconformity

http://www.wwnorton.com/college/geo/egeo2/content/animations/10_4.htm

 

2.  Nonconformities

Click here for another nonconformity

http://www.wwnorton.com/college/geo/egeo2/content/animations/10_4.htm

3.  Angular Unconformities

Click here for animation of an angular unconformity

Click here for another angular unconformity

Click here for an animation of an angular nonconformity

http://www.wwnorton.com/college/geo/egeo2/content/animations/10_4.htm

 

 

Questions:

1.  Describe how a disconformity forms.

2.  Describe how an angular unconformity forms.

3.  Describe how a nonconformity occurs?  (Hint:  what type(s) of rock)

4.  How do a nonconformtiy and a disconformity differ?

5.  Complete the table

Type of unconformity Nonconformity Disconformity Angular Unconformity
Sketch
Notes

 

 STOP HERE END OF 12.1 NOTES

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Week 2

Vocabulary for week 2:

  1. extinct
  2. fossil
  3. principle of fossil succession
  4. theory of evolution
  5. natural selection
  6. adaptation
  7. index fossil

Week 2 Objectives

What are the different types of fossils? (p. 342-43)

  1. petrified
  2. molds and casts
  3. carbon films
  4. preserved remains
  5. trace fossils

What two conditions help a fossil to form? (p. 344)

  1. rapid burial
  2. possession of hard body parts

What two major developments helped scientists explain the fossil record? (344-345)

  1. principle of fossil succession
  2. the theory of evolution

How do geologists interpret fossils and rocks? (p. 345-347)

  1. improve the correlation of rock layers
  2. to reconstruct past environments

What is an index fossil?  What are 4 characteristics of an index fossil?

A fossil associated with a specific period of geologic time

  1. existed for a limited span of time
  2. geographically widespread
  3. abundant
  4. unique looking

 STOP HERE END OF 12.2 NOTES

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Week 3 Notes

Ch 12.4 The Geologic Time Scale

Vocabulary for week 3:

  1. geologic time scale
  2. eon
  3. era
  4. period
  5. epoch
  6. Precambrian time

Describe and explain geologic time (eras only) p. 353-357 and 369-387

What is the geologic time scale?  p.353

A record that includes both geologic events and major developments in the evolution of life.

How is the geologic time scale constructed?  p. 353-355

Eons represent the longest interval.  Eons are divided into eras, eras are divided  into periods, and periods are divided into epochs.

  • Eon = year
  • Era = month
  • Period = week
  • Epoch = day

Geologists use fossil to

  1. improve the correlation of rock layers
  2. reconstruct past environments

Use this link to view the geologic time scale drawn to scale.  Hint:  Look at the first column.

Know the difference between relative time and absolute time.  The information is in the paragraphs below the time scale.

Link to Geologic Time Scale

 

A link from USGS -US Geological Survey

The link below is great for dates and events

Another helpful link

Questions:

1.  Which time period lasted the longest? The shortest?

2.  How many years ago did the Precambrian era begin?

3.  How many years ago did the Paleozoic era begin?

4. How many years ago did the Mesozoic era begin?

5.  How many years ago did the Cenozoic era begin

6.  Use the first link to sketch the Precambrian, Paleozoic, Mesozoic, and Cenozoic to scale.  Please note:  The sketch in you text is NOT DRAWN TO SCALE!!!!!!!

 

 STOP HERE END OF 12.4 NOTES

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Week 4 Notes

Ch 12.3

Vocabulary for week 4:

  1. radioactivity
  2. half-life
  3. radiometric dating
  4. radiocarbon dating

Week 4 Objectives

What happens during radioactive decay?  p. 347

unstable atomic nuclei spontaneously decay, releasing energy

How are isotopes used in radiometric dating? p. 348-349

Scientists measure the ration between radioactive parent element and daughter products in the sample to be dated.  The older the sample, the more daughter product it contains.

How can radiometric dating be used to date organic material?  p. 350

When an organisms dies, the amount of carbon-14 gradually decreases as it decays.  By comparing C-14 to C-12 ratios, radiocarbon dates can be determined

How can radiometric dating be used to date sedimentary rock? p. 350

Geologists must relate sedimentary rock to datable masses of igneous rock.

Questions:

Click this link for animations to answer the following questions.

Click “Run Now” which is located below the picture.

PART 1:  When the program appears, click the tab for “Decay Rates”.

Carbon-14 (the unstable parent) is represented by red while nnitrogen-14 (the stable daughter) is represented by blue.

1.  What happens to the total amount of carbon-14 as the simulation plays?  What happens to the total amount of nitrogen-14?

2.  Examine the graph.  After the…

first half life, ____% of carbon-14 remains while ____ % of nitrogen-14 had formed.

second half life, ____% of carbon-14 remains while ____ % of nitrogen-14 had formed.

third half life, ____% of carbon-14 remains while ____ % of nitrogen-14 had formed.

PART 2:  Now click the tab for “Measurement”  Begin by planting the tree

3. What percent of carbon-14 is found in the live tree?

4.  What happens to the amount of carbon-14 after the tree dies?

5.  Estimate the approximate half-life of carbon-14.

Repeat but this time use uranium to date the tree.

6.  Is uranium-238 as useful as carbon-14 in dating a tree? Explain.

Now date the rock using uranium

7. What percent of uranium-238 is found in the “hot” rock?

8.  What happens to the amount of uranium-238 after the rock “cools”?

9.  What is the approximate half-life of uranium-238?

Now date the rock using carbon-14

10.  Is it possible to use carbon-14 to date an igneous rock?  Explain

11.  Write a general rule on when it is appropriate to use carbon-14 and when is it appropriate to use uranium-238 to date particular types of objects.

PART 3:  Use the tab “Dating Game” to complete your handout.

Use this link for computer activity on the separate yellow page.

http://phet.colorado.edu/en/simulation/radioactive-dating-game

 

STOP HERE END OF 12.3 NOTES

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Week 5 Objectives

13.1 Notes

Vocabulary week 5:

  1. shields
  2. photosynthesis
  3. stromatolites
  4. prokaryotes
  5. eukaryotes

Describe how land, atmosphere, and oceans resulted from the evolution of the Earth system p. 364-368

What were the major geologic developments during the Precambrian time? p. 364-366

The Earth formed 4.56 billion years ago.

During the Precambrian…

  • The Earth formed.  Gravity pulled dust, ice, and rock together in space.  Impact from rocks as wells as radioactive decay produced heat and the melted Earth began to form layers.  As Earth cooled, the core, mantle, and crust formed.
  • The atmosphere formed.  Early atmosphere was similar to gases released in volcanic eruptions (high CO2, water vapor, and nitrogen).  Later, life forms converted much of the CO2 into oxygen
  • The oceans formed. As planet cooled, water vapor from air cooled and conensed into liquid water
  • The continents developed.  Convection inside the Earth drove tectonic activity which developed the continents.

What were the major developments in living things during Precambrian time?  p. 367-368

  • Earliest life probably developed in the oceans.
  • Later, one celled organisms used photosynthesis to convert CO2 into food and oxygen changing the Earth’s atmosphere
  • Slowly, more complex eukaryotes developed.
  • Late in Precambrian, soft-bodied multi-celled organisms evolved.

Questions:

Print the Geologic timeline from this link.  Scroll down to the PDF copy.  You will takes notes on it later today.

 

Use this link to answer the questions.

http://www.scotese.com/precamb_chart.htm

Examine the graph of the Precambrian.

 

1.  What gas was in greatest abundance at the beginning of the Precambrian?

 

2. What happens to the abundance of that gas during the Precambrian?

 

3.  Stromatolites are photosynthetic organisms.  Through photosynthesis, they consume CO2 and produce oxygen as waste.

 

4.  What do you notice about the appearance of stromatolites and the amount of CO2?

 

5.  What do you notice about the appearance of stromatolites and the amount of oxygen?

 

6.  When did the “Global Ice Age” occur?

CAMBRIAN

 

Link for Cambrian

 

6. Animals with ___________________ appeared in great numbers for the first time during the Cambrian.

7.  The continents were flooded by _____________.

8.  The supercontinent of _________________ had just formed and was located near the South Pole.

 

K/T Extinction.

Click link

9.  Describe the Chicxulub impact site.

10.  Why do scientists think this may have caused extinction of dinosaurs?

11.  The geologic time scale in NOT divided into increment of equal time like our calendar.  What marks the end of each unit of time?

12. Now.  Using the geologic timeline that you printed, read each period and jot down a note about something important that happened during that period.

END OF 13.1 NOTES. STOP HERE!!

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  • Video:  Nat Geo The History of the Earth Parts 1-3
  • http://www.youtube.com/watch?v=H6OuD877Rog
  • http://www.youtube.com/watch?v=C9Vw0vHdAB4
  • http://www.youtube.com/watch?v=zxzLnjoQGDY
  • http://www.youtube.com/watch?v=ULEYXB_0D9o
  • http://www.youtube.com/watch?v=bk0pr-lgf6A
  • http://www.youtube.com/watch?v=hD-JeeK4a9E
  • http://www.youtube.com/watch?v=AH4EiaVULwU
  • http://www.youtube.com/watch?v=DxER2pGXLn4
  • http://www.youtube.com/watch?v=2X2CMsUhL3g
  • http://www.youtube.com/watch?v=BqpB3GHtmhI

By mmorrow 7:03 am