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Flashcards in Chapter 9 Deck (32):
1

The first win of Precambrian time. The eon prece ding the protozoic. It extends between 4.5 and 2.5 billion years ago

Archean Eon

2

A time span on the geologic time scale beginning about 6.5 million years ago, following the Mesozoic era

Cenozoic Era

3

Rock layers that were deposited without interruption

Conformable

4

The process of establishing the equivalence of rocks of similar age in different areas

Correlation

5

A principle of relative dating. A rock or fault is younger than any rock (or fault) through which it cuts

Cross-Cutting Relationship

6

A type of unconformity in which the beds above and below are parallel

Disconformity

7

The largest unit of time on the geologic scale, next in order of magnitude above area

Eon

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A unit of the geologic time scale that is a subdivision of a period

Epoch

9

A major division on the geologic time scale; are divided into shorter units called periods

Era

10

The remains of traces of organisms preserved from the geologic past

Fossil

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The definite and determinable order in which fossil organisms occur. enables us to identify many time periods by their fossil content

Fossil succession, principle of

12

The division of Earth History into blocks of tie-eons, eras, periods, and epochs. The time scale was created using relative dating principles.

Geologic Time scale

13

The earliest time interval (eon) of Earth history. The time before the planet's first rocks.

Hadean Eon

14

The time required for one half of the atoms of a radioactive substance to decay

Half-life

15

A piece of one rock unit that is contained within another. Are used in relative dating.

Inclusions

16

A fossil that is associated with a particular span of geologic time.

Index Fossil

17

A time span on the geologic time scale between the Paleozoic and Cenozoic eras from about 248 to 65.5 million years ago.

Mesozoic Era

18

An unconformity in which older metamorphic or intrusive igneous rocks are overall by younger sedimentary strata

Nonconformity

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The number of years that have passed since an event occurred

Numerical (absolute) dating

20

Layers of sediment that are generally deposited in a horizontal or nearly horizontal position

Original horizontality, principle

21

The systematic study of fossils and the history of life on Earth

Paleontology

22

A time span on the geologic time scale between the Precambrian and Mesozoic eras - from about 542 million to 252 million years ago

Paleozoic Eon

23

A basic unit of the geologic time scale that is a subdivision of an era. May be divided into smaller units called epochs.

Period

24

An unconformity in which the older strata dip at an angle different from that of the younger beds

Angular unconformity

25

All geologic time prior to the Phanerozoic eon. A term encompassing both the Archean and Protozoic eons.

Precambrian

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The eon following the Archean and preceding the Phanerozoic. It extends between 2500 and 542 million years ago.

Proterozoic Eon

27

The spontaneous decay of certain unstable atomic nuclei

Radioactivity

28

The procedure of calculating the absolute ages of rocks and minerals that contain certain radioactive slopes

Radiometric dating

29

A process of determining the chronological order of events by placing rocks and structures in the proper sequence or order

Relative dating

30

A surface that represents a break in the rock record, caused by erosion and non-deposition

Unconformity

31

Dating of events from the very recent geologic past (the past few tens of thousands of years) based on the facet that the radioactive isotope of carbon is produced continuously in the atmosphere

Carbon-14 dating

32

In an unreformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below

Superposition, principle of