1. Geologic Evidence of Change Over Time - FOSSILS
Wake County
8th Grade
Science Curriculum

2. Fossil: preserved remains or traces of living things
Most fossils form when living things die and are buried by sediment; over time the sediments harden
Fossils are only found in sedimentary rock. WHY?

3. Change Over Time Geologic Evidence
Different kinds of fossils are:
1. Mold: a hollow area in sediment in the shape of an organism or part of an organism; formed when the organism makes an indentation that turns to rock over time
Cake mold

4. Change Over Time Geologic Evidence
Cast: a solid copy of the shape of an organism; made by filling in a mold with minerals that later turn to rock.
esp.cr.usgs.gov
Mold Cast

5. Change Over Time Geologic Evidence
2. Petrified fossil: minerals replace all or part of an organism
en.wikivisual.com
You can see the rings.

6. Change Over Time Geologic Evidence
3. Carbon film: an extremely thin coating of carbon on rock; made when an organism is squeezed by rock until only carbon remains

7. Change Over Time Geologic Evidence
4. Trace fossil: evidence of activities of ancient organisms; may be tracks, burrows, nest, or trail
igs.indiana.edu
Fossil burrow
Fossil tracks

8. Change Over Time Geologic Evidence
5. Preserved Remains
Amber: a hardened resin, or sap, of evergreen trees; organisms that get trapped in the sticky substance becomes part of the rock
pixdaus.com

9. Change Over Time Geologic Evidence
Frozen remains: organisms caught in ice or snow Adult mammoth
Frozen baby mammoth
flickr.com

10. Change Over Time Geologic Evidence
Fossil record: the complete body of fossils that shows how species and ecosystems change over time
anthropology.net
images.mooseyscountrygarden.com

11. Change Over Time Geologic Evidence
The fossil record shows that fossils occur in a particular order: older rocks contain simpler organisms and younger rocks contain more complex organisms. WHY??
The fossil record provides evidence to support evolution (the gradual change in living things over long periods of time).
{Everything we are studying shows evolution as a change over time – do not bring religion into it  We have to teach the curriculum. Everything is a scientific theory. What does this mean?}

12. Change Over Time Geologic Evidence
How do fossils give us the age of organisms that lived in the past?
Is this fish fossil a few thousand years old or a few billion years old?

13. Law of Superposition
The Law of Superposition: a given rock layer is older than the rock layer above it.
Think about your dirty clothes in your laundry basket? Where is the oldest clothes compared to the clothes you wore yesterday?

14. Uniformitarianism
Geologic process that happened in the past that are still present now.
Examples:
Weather and erosion today also shaped Earths surface millions of years ago
Continental Drift…continues today as it did millions/billions of years ago

15. Change Over Time Geologic Evidence
Dating Rocks and Fossils
Relative Dating: uses information about rock layers and the fossil record to determine the age relationships between rocks
Absolute Dating: any method of measuring the age of an event or object in years