1. Geologic History Vocabulary Test
Chapter 13 & 14

2. remains, imprints, or traces of once-living organisms#1
remains, imprints, or traces of once-living organisms

3. fossils of species that existed for short periods and were widespread#2
fossils of species that existed for short periods and were widespread

4. cavity in rock made when an organism decayed#3
cavity in rock made when an organism decayed

5. #4
method by which order of events or age of rocks is determined by examining the position of rocks in a layer

6. #5
formed when original materials in skeletal remains are replaced by minerals

7. #6
states that in a sequence of undisturbed rocks, the oldest rocks are on the bottom and the rocks become progressively younger toward the top

8. produced when sediments fill in a cavity made when an object decayed#7
produced when sediments fill in a cavity made when an object decayed

9. #8
process that uses the properties of atoms in rocks and other objects to determine their ages

10. fossil of thin layer of carbon atoms and molecules#9
fossil of thin layer of carbon atoms and molecules

11. #10
gaps in rock record made when agents of erosion remove existing rock layers

12. time it takes for half of an isotope's atoms to decay
#11
time it takes for half of an isotope's atoms to decay

13. #12
method by which a geologist can calculate the absolute age of the rock by knowing the half-life of an isotope

14. #13
principle that earth's processes occurring today are similar to those that occurred in the past

15. #14
process that occurs when the number of protons in an atom is changed and a new element is formed

16. #15
one of four major subdivisions of geologic time-the longest subdivision (based upon the abundance of certain fossils)

17. division of Earth's history into smaller units
#16
division of Earth's history into smaller units

18. #17
one of four major subdivisions of geologic time-characterized by the types of life existing worldwide at the time

19. #18
one of four major subdivisions of geologic time-second longest subdivision (marked by major, striking, worldwide changes in the types of fossils present

20. #19
one of four major subdivisions of geologic time-characterized by differences in life-forms which can vary from continent to continent

21. #20
used to study the passage of geologic time because of changes in their physical features through time

22. #21
a group of organisms that normally reproduces only with other members of their group

23. #22
blue-green algae thought to be one of the earliest forms of life on Earth

24. giant landmass or supercontinent meaning "all land"
#23
giant landmass or supercontinent meaning "all land"

25. #24
longest part of Earth's history-includes the Hadean, Archean, and Proterozoic Eons (4.5 billion yrs. ago to about 544 million yrs. ago)

26. #25
(era of middle life) time of many changes on Earth (Pangaea)-from 248 million years ago to 65 million years ago

27. #26
(era of recent life) began about 65 million years ago and continues today

28. #27
(era of ancient life) began about 544 million years ago and ended about 248 million years ago