Geologic Time

Question 1

means that the forces and processes that we observe today have been at work for a very long time. This means that the forces that keep on changing Earth have been working for very long periods of time since the beginning of Earth’s history.

Answer 1

uniformitarianism

Question 2

a Scottish geologist, proposed the principle of uniformitarianism

Answer 2

James Hutton

Question 3

james hutton quote

Answer 3

“the present is the key to the past”

Question 4

relative dating is determined by

Answer 4

stratified rocks
fossils

Question 5

absolute dating is measured by

Answer 5

radioactive dating
fossils

Question 6

A method of showing the sequence of events; that is, which happened first, next, and so on. For example, the rocks beneath a volcano were formed much ahead of the volcano, which means that a volcano is younger than the rocks beneath it.

Answer 6

relative dating

Question 7

science that deals with the characteristics of layered rocks and how these rocks are used to trace Earth’s history

Answer 7

stratigraphy

Question 8

formed over time by wind, rain and glacial formations. These rocks may be formed by folding and tilting, faulting, and volcanic intrusions.

Answer 8

stratified rocks

Question 9

studied the relative positions of sediments in sedimentary rocks.

Answer 9

nicolas steno

Question 10

states that in an undeform sequence of sedimentary rocks, each bed is older than the one above it and younger than the one below it.

Answer 10

law of superposition

Question 11

states that sediments are deposited in flat layers. Thus, if the rock still maintains its horizontal layers, it means that it is not yet disturbed and still has its original horizontality.

Answer 11

Principle of Original Horizontality

Question 12

states that when a fault cuts through rock layers, or when magma intrudes other rocks and crystallizes, we can assume that the fault or intrusion is younger than the rocks affected.

Answer 12

Principle of Cross-Cutting Relationships

Question 13

Inclusions are rocks contained within other rocks. Rocks containing inclusions are younger than the inclusions they contain.

Answer 13

inclusions principle

Question 14

rock layers that formed without interruption.

Answer 14

conformable

Question 15

a layer of rock that was deformed or eroded before another layer was deposited, resulting in rock layers that are mismatched.

Answer 15

uncomformity

Question 16

younger sediments rest upon the eroded surface of tilted or folded older rocks.

Answer 16

angular uncomformity

Question 17

contact between younger and older beds is marked by a visible, irregular or uneven erosional surface.

Answer 17

disconformity

Question 18

beds above and below the unconformity are parallel and no erosional surface is evident; but can be recognized based on the gap in the rock record.

Answer 18

paraconformity

Question 19

develops between sedimentary rock and older igneous or metamorphic rock that has been exposed to erosion.

Answer 19

nonconformity

Question 20

is establishing the equivalence of rocks of similar age in different areas.

Answer 20

correlation

Question 21

a system of chronological dating that relates rock strata to time.

Answer 21

geologic time scale

Question 22

is the science that deals with the study of fossils.

Answer 22

paleontology

Question 23

are the remains or traces of prehistoric life. They are important components of sediment and sedimentary rocks.

Answer 23

fossil

Question 24

Some remains of organisms—such as teeth, bones, and shells—may not have been altered, or may have changed hardly at all over time.

Answer 24

unaltered remains

Question 25

The remains of an organism are likely to be changed over time.

Answer 25

altered remains

Question 26

are the actual remains that did not change through time like teeth, bones, and shells of animals.

Answer 26

true form fossil

Question 27

or fossils that turned into stone were formed when all or parts of organisms were replaced by minerals.

Answer 27

petrified fossil

Question 28

preserve the form and shape of organisms. Molds are formed when organisms buried in sediments decay or dissolve. When minerals are deposited within the molds, casts can be formed.

Answer 28

molds and casts

Question 29

result from a process undergone by leaves and delicate animal forms, through which they are covered with fine sediments.

Answer 29

carbonized fossil

Question 30

is the hardened resin of ancient trees where insectsare preserved.

Answer 30

amber/preserved

Question 31

states that the fossils of organisms succeed one another in a specific and well-established order, and that any geologic time or period can be recognized by the kind of fossil present.

Answer 31

Principle of Fossil Succession

Question 32

The principle of fossil succession was formulated by

Answer 32

william smith

Question 33

are fossils of organisms that lived only for a short period of time and are found in most places on the planet.

Answer 33

index fossil

Question 34

A methods, sometimes called numerical dating, gives rocks an actual date or date range in number of years.

Answer 34

absolute dating

Question 35

are atoms of the same element having the same number of protons but with different numbers of neutrons in their nuclei.

Answer 35

isotopes

Question 36

the forces among the particles that makeup the nucleus are balanced.

Answer 36

stable

Question 37

these forces are unbalanced; if the nucleus has an excess of either neutrons or protons.

Answer 37

unstable

Question 38

is the spontaneous decay of certain unstable atomic nuclei.

Answer 38

radioactivity

Question 39

is the amount of time necessary for one-half of the nuclei in a sample to decay to a stable isotope.

Answer 39

half life

Question 40

is a type of radioactive disintegration in which some unstable atomic nuclei dissipate excess energy by spontaneously ejecting an alpha particle.

Answer 40

alpha emission

Question 41

occurs when the ratio of neutrons to protons in the nucleus is too high. An excess neutron transforms into a proton and an electron. The proton stays in the nucleus and the electron is ejected energetically

Answer 41

beta emission

Question 42

occurs when there are too many protons in the nucleus, and there isn’t enough energy to emit a positron.

Answer 42

electron capture

Question 43

is the procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopes.

Answer 43

radiometric dating

Question 44

is the method for determining age by comparing the amount of carbon-14 to the amount of carbon-12 in a sample.

Answer 44

radiocarbon dating