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© Fall 2005, Pflugerville ISD, 8th Grade 8th Grade Science.

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Presentation on theme: "© Fall 2005, Pflugerville ISD, 8th Grade 8th Grade Science."— Presentation transcript:

1 © Fall 2005, Pflugerville ISD, 8th Grade 8th Grade Science

2 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Chapter 16- The Rock & Fossil Record Section 1: Earths Story & Those Who First Listened Section 2: When on Earth? Section 3: Looking at Fossils Section 4: Time Marches On

3 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 The present is the key to the past. -James Hutton We study the past because if we dont, we are doomed to repeat it. But how can studying the present help us understand earths history? What are some processes you can see today that also occurred millions of years ago? What Do You Think?

4 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened James Hutton The present is the key to the past. Father of modern geology

5 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Hadrians Wall, England Hutton knew that Hadrians wall was built by the Romans in historical times

6 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Hadrians Wall, England Only 1600 years old, the wall was already starting to weather and erode

7 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Arthurs Seat Volcano, Edinburgh, Scotland Hutton wondered how long it would take to erode a mountain

8 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Arthurs Seat Volcano, Edinburgh, Scotland Hutton decided that it would take millions of years, making the earth very ancient

9 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Arthurs Seat Volcano, Edinburgh, Scotland Hutton realized that erosion and deposition have been going on for a long time

10 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened James Hutton Uniformitarianism is Huttons belief that geologic processes are uniform and do not change over time

11 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened James Hutton Huttons views of a billion-year-old earth clashed with most scientists belief in catastrophism

12 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Most scientists supported catastrophism, the idea that all geologic change happens quickly

13 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened These scientists used huge floods, eruptions and catastrophes to explain rapid geologic change

14 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened Today, scientists think that sudden events are the cause of some changes in earths past

15 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Earths Story & Those Who Listened But they agree that the earth is billions of years old, and that most change is gradual

16 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? Suppose your friend piles his stuff on his floor and never cleans his room. Under the top layer of clothes, you find a pizza box. Under this is a bunch of CDs then some homework and under this is a ham sandwich. Arrange these four layers from oldest to youngest… What Do You Think?

17 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? Grand Canyon The Principle of Superposition states that younger rocks lie over older rocks

18 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? Grand Canyon The Principle of Superposition is used to find the relative ages of rock layers

19 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? The Law of Cross-Cutting Relationships can tell geologists the relative age of a fault or intrusion

20 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? The dike is the youngest feature, because the other layers were cut by it

21 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Relative Dating Use your knowledge to order the layers, faults and intrusions in the next slide from oldest to youngest

22 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Relative Dating

23 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Relative Dating James Hutton Geologists can use rock layers from many locations to create a geologic column

24 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Relative Dating

25 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Relative Dating The geologic column is an ideal sequence of rock layers that contains all known rock formations and fossils on Earth

26 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 When on Earth? Huttons Unconformity An unconformity is a surface that represents a missing part of the geologic column

27 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Formation of an Unconformity Million Years Ago Sediment is eroded from a hill and deposited in a valley

28 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Formation of an Unconformity 15-5 Million Years Ago The area is uplifted and exposed to erosion, then the land surface is eroded away

29 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Formation of an Unconformity 5 Million Years Ago- Present Deposition resumes Can you spot the unconformity?

30 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Absolute Dating When animals eat, they ingest radioactive Carbon-14

31 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Absolute Dating Carbon-14 decays into Nitrogen-14 Carbon-14 Nitrogen-14

32 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Absolute Dating By comparing the amount of C-14 to N-14, geologists can calculate the age of a fossil

33 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 2 Absolute Dating Since C-14 has a half-life of only 5730 years, other isotopes are used to date older rocks

34 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 1 Absolute Dating James Hutton The oldest rocks on Earth have been dated to 4.5 billion years, confirming Huttons beliefs

35 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Imagine that a geologist 65 million years from now has unearthed fossils of your life. What would she find? What Do You Think?

36 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Saber-Tooth Cat Fossil A fossil is the remains or physical evidence of an organism preserved by geologic processes

37 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Fossil Amber with Insect Inclusions Fossilized tree sap is called amber

38 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Fossil Amber with Insect Inclusions Animals caught in amber are perfectly preserved

39 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Woolly Mammoth Fossils of mammoths, extinct for 12,000 years, have been found frozen in Arctic ice

40 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Theropod Track A trace fossil is naturally preserved evidence of animal activity

41 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Theropod Track This dinosaur track is located in Glen Rose, Texas, in Dinosaur Valley State Park

42 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Ammonite Fossil A mold is a cavity in rock where a plant or animal was buried

43 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Ammonite Fossil A cast is an object made when sediment fills a mold and becomes rock

44 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils

45 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Ammonite Fossil Which of these is the mold and which is the cast?

46 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Whale Bones Most animals are not buried fast enough to form fossils

47 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Whale Bones These whale bones will be broken down before they can form fossils

48 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Trilobite Fossil The trilobite Phacops lived for a short time 400 million years ago

49 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Trilobite Fossil An index fossil is one found for a short time in rock layers around the world

50 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 3 Looking at Fossils Trilobite Fossil If Phacops is found in a rock layer, the rock must be about 400 million years old

51 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On If the history of Earth were the length of one calendar year, on what date do you think modern humans arrived? What Do You Think?

52 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Humans First Arrived Humans evolved in the last half-hour of New Years Eve!

53 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On The Geologic Time Scale divides Earths history into eons, eras, & periods

54 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Since most fossils are from the Phanerozoic Eon, this is the eon that is given the most attention

55 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On The Phanerozoic is actually the shortest of the four eons

56 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Paleozoic Era mya In the Paleozoic Era, life in the oceans, as well as all major plant groups, flourished

57 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Mesozoic Era mya With a mass extinction at the end of the Paleozoic, the remaining reptiles thrived

58 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Mesozoic Era mya Known as the Age of Reptiles, birds and small mammals appeared late in the Mesozoic

59 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Cenozoic Era 65 mya- Present Mammals flourished after a mass extinction killed the dinosaurs

60 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 : Section 4 Time Marches On Cenozoic Era 65 mya- Present The Cenozoic is known as the Age of Mammals

61 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Lets Review! What did James Hutton mean by the comment, The present is the key to the past?

62 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Lets Review! How can you tell the age of rocks and fossils?

63 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Lets Review! How is a fossil created? Describe how a geologist would use an index fossil…

64 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Lets Review! What type of event ended both the Paleozoic and Mesozoic Eras? What geologic time period was occurring 200 million years ago?

65 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16

66 © Fall 2005, Pflugerville ISD, 8th GradeUnit 4 : Chapter 16 Pre-AP Extensions


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