Earth Science 11^th Edition Vocabulary Chapter 11

By Reshawn Brown (GLY 1001 Student North Campus Fall 2006)

1. angular unconformity(p.315) – An unconformity in which the strata below dip at an angle different from that of the beds above.

2. catastrophism (p.311) – The concept that Earth was shaped by catastrophic events of short-term nature.

3. Cenozoic era (p. 327) – A span on the geologic time scale beginning about 65 million years ago following the Mesozoic era.

4. conformable (p.315) – Layers of rock that were deposited without interruption

5. correlation (p. 316) – Establishing the equivalence of rocks of similar age in different areas

6. cross-cutting relationships, principle of (p.314) – A principle of relative dating. A rock or fault is younger than any rock (or fault) through which it cuts.

7. disconformity (p.315) – A type of unconformity in which the beds above and below are parallel

8. eon (p. 327) – The largest time unit on the geologic time scale, next in order of magnitude above era.

9. epoch (p.327) – A unit of the geologic calendar that is a subdivision of a period.

10. fossil (p.317) – The remains or traces of organisms preserved from the geologic past.

11. fossil succession, principle of (p.321) – Fossil organisms that succeed one another in a definite and determinable order, and any time period can be recognized by it fossil content

12. geologic time scale (p. 327) – T he division of Earth history into blocks of time--- eons, eras, periods, and epochs. The time scale was created using relative dating principles

13. half-life (p.324) – The time required for one half of the atoms of a radioactive substance t decay

14. inclusions (p.314) – A piece of one rock unit contained within another. Inclusions are used in relative dating. The rock mass adjacent to the one containing the inclusion must have been there first in order to provide the fragment.

15. index fossil (p.321) – A fossil that is associated with a particular span of geologic time.

16. Mesozoic era (p.327) – A span on the geologic time scale between the Paleozoic and Cenozoic eras from about 248 million to 65 millions years ago

17. nonconformity (p.312) - A n unconformity in which older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata

18. numerical date (p.313) – Date that specifies the actual number of years that have passed since an event occurred

19. original horizontally, principle of (p.313) – Layers of sediments are generally deposited in a horizontal or nearly horizontal position

20. paleontology (p.317) – The systematic study of fossils and the history of life on Earth

21. Paleozoic era (p.327) – A span on the geologic time scale between the eons of the Precambrian and Mesozoic era from about 540 million to 248 million years ago

22. period (p.327) – A basic unit of the geologic calendar that is a subdivision of an era. Periods may be divided into smaller units called epochs.

23. Phanerozoic eon (p. 327) – That part of geologic time represented by rocks containing abundant fossil evidence. The eon extending from the end of the Proterozoic eon ( about 540 million years ago) to the present.

24. Precambrian (p.328) – All geologic time prior to the Paleozoic era.

25. radioactivity (p.323) – The spontaneous decay of certain unstable atomic nuclei

26. radiocarbon dating (p. 325) – The radioactive isotope of carbon, which is produced continuously in the atmosphere and is used in dating events from the very recent geologic past(the last few tens of thousands of years)

27. relative dating ( p. 312) – Rocks are placed in their proper sequence or order. Only the chronological order of events is determined

28. superposition, law of (p. 313) – In any undeformed sequence of sedimentary rocks, each bed is older than the layers below.

29. unconformity (p.315) – A surface that represents a break in the rock record, caused by erosion or nondeposition

30. uniformitarianism (p.311) – The concept that the processes that have shaped Earth in the geologic past are essentially the same as those operating today.