Name: ________________________
Period:___________________
Study Guide
Chapter 6 – Paleontology/Fossils
1.
2.
3.
4.
5.
6.
Be able to tell which unconformity is older. From picture on page 139-140
What divides Earth’s history into distinct intervals of time? Geologic Time Scale
The time it takes for one-half of the radioactive sample to decay is called. Half-life
Define Isotope: atoms of same element different number of neutrons.
What occurs when rock layers bend and buckle from Earth’s internal forces? folding
What is the sequence of rock layers called that contains all known fossils and rock
formations? Geologic Column
7. Define unconformity: Erosion and non deposition are causes for unconformity
8. What eon do we live in? Phanerozoic Eon
9. What era is the age of the mammals? Cenozoic
10. What is the largest division of geologic time? Eons
11. What is a burrow? A fossilized shelter made by an animal that dug into the ground
12. How do we know so much about the saber-toothed tiger? Tar
13. Which type of carbon is a radioactive isotope? Carbon 14
14. Angular unconformity exists between horizontal rock layers and rock layers that are tilted
or folded.
15. What are missing rock layers that create gaps in rock-layer sequences? Unconformities
16. What type of dating determines whether an object or event is older or younger than other
objects? Relative dating
17. Which theory do modern geologists embrace about how the Earth changes?
Uniformitarianism
18. Define catastrophism: change occurs suddenly
19. Be able to identify a trace fossil example. A mark left by a dinosaur’s tail.
20. If Earth’s history is put on a scale of 12 hours, human civilizations would have been
around for less than a second.
21. What is the shortest geologic time interval? Epoch
22. How do fossils form? Petrified, dried out, Frozen
23. Which isotope has the longest half-life? Uranium-238
24. What era is known as the age of the reptiles? Mesozoic
25. Which era is known as the first land-dwellers? Paleozoic
26. What time scale comes after periods? Epochs
27. Define cast: is an object created when sediment fills a mold.
28. Define mold: is a cavity in ground or rock where plant and animals were buried.
29. What is the stuff called where a fossil hardens in tree sap? Amber
30. What is the process in which trees fossilize? Petrified Wood
31. Define absolute dating: Process of establishing the age of an object such as a fossil.
32. Define relative dating: Determines whether an object or event is older or younger than the
other events.
33. Be able to look at a picture and answer questions about superposition, faulting, folding,
relative age, and intrusions.
34. What is the most common type of unconformity? Disconformity
35. Define Uniformitarianism.: Principal that geologic processes have been at work
throughout Earth’s history
36. What process always occurs at a constant rate? Radioactive decay
37. How old is the Earth? 4.6 billion years
38. Which method of dating would scientists use to determine the most accurate and precise
age of Earth’s objects? Uranium-lead
Name: ________________________
Period:___________________
39. Be able to determine how much of an unstable element will be left over after two halflives. ¼ or 25%