The study of the spatial and temporal relationships between bodies of rock is called ____________________.
stratigraphy
The geological time scale is the ____________ framework in which geologists view Earth history.
temporal
Both _________________ and absolute scales are included in the geological time scale.
relativistic
Beds represent a depositional event. They are _________ 1 cm in thickness.
greater than
Laminations are similar to beds but are ___________ 1 cm in thickness.
less than
The idea that most beds are laid down horizontally or nearly so is called the
Principle of Original Horizontality
The idea that beds extend laterally in three dimensions until they thin to zero thickness is called the
Principle of Original Continuity or simple the Principle of Continuity
The idea that younger beds are deposited on top of older beds is called the
Principle of Superposition
The idea that a dike transecting bedding must be younger than the bedding it crosses is called the
Principle of Cross-Cutting Relationships
The idea that fossil content will change upward within a formation is called the
Principle of Fossil Succession
An unconformity represents an absence of ________________ due to erosion or non- deposition.
sedimentation
What does surface AB represent in the following illustration? (triangular orange and yellow figure)
angular unconformity
What does surface ABC represent in the following illustration? (brown and red figure)
nonconformity
What does surface ABC represent in the following illustration? (tan and blue figure)
disconformity
A unit that displays a different lithological aspect relative to rocks above and below is called a __________________________________ unit.
rock-stratigraphic unit
The most common rock-stratigraphic unit is the _________________.
formation
Formations can be subdivided into ___________________.
members
Members can be subdivided into ___________________.
beds
Two or more formations compose a ___________________.
group
All rocks around the globe that formed during the same interval of time form a _________________________________ unit.
time-stratigraphic
Which of the following is not a time-stratigraphic unit?
(a) eonothem
(b) erathem
(c) system
(d) series
(e) none of the above
none of the above
The primary time-stratigraphic unit is the ___________________.
system
system is subdivided into ___________________.
series
The stage is the ________________ subdivision of time-stratigraphic units.
smallest
The eonothem is the ________________ subdivision of time-stratigraphic units is the.
largest
Paleontologists have traced the lineage of Homo back to Australopithecus afarenses. This now extinct ancestor of Homo lived in the Paleocene between about _______ and _______ million years ago.
4, 2.7
Geological time units correspond to the time that a specified _____________________ was deposited.
time-stratigraphic unit
The geologic-time unit representing the longest interval of time is the __________.
eon
The geologic-time unit representing the smallest interval of time is the ____________.
age
The geologic-time unit corresponding to the time that a system was deposited is the ___________.
period
The geologic-time unit corresponding to the time that a series was deposited is the __________.
epoch
The geologic-time unit corresponding to the time that an erathem was deposited is the ___________.
era
The geologic-time unit corresponding to the time that an eonothem was deposited is the ___________.
eon
Geologists use both ____________ and ____________ criteria to correlate strata.
physical, biological
What is the oldest age obtained from a mineral or rock on our planet?
4.4 billion years
How old is the Acasta gneiss and why is it significant?
4.03 billion years- oldest dated rocks on planet Earth
Why is the evolution of the cyanobacteria important to the evolution of an oxygen-rich atmosphere on planet Earth?
Cyanobacteria utilized photosynthesis to convert light into chemical energy. The products of
this process are glucose and oxygen. Hence, cyanobacteria were essential for the development
of an oxygen-rich atmosphere.
During the Proterozoic, between about ________ billion years and _________ million years ago, the development of multicellular organisms with nuclei developed. These organisms eventually led to the development of the plants, spiders, fungi, and protists,
2.5, 543, (c) eukaryotes
The first life forms on planet Earth occur during the Archean between about _______ and _______ billion years ago, and are called
4.0, 2.5, (d) prokaryotes
What is the age of the Earth?
4.6 billion years
The first animals with preservable hard parts first appear in the _______________?
Cambrian
Why is Cooksonia significant, and in what approximate time range did it evolve?
first vascular land plant - evolved approximately 443 - 417 million years ago
In what system is Cooksonia first found?
Silurian
During ____________________ there were there vast swamps and peat bogs in the eastern and mid-western US. This period lasted from _________ to __________ million years ago.
Pennsylvanian, 323, 290
What is Rodinia?
first supercontinent to form on planet Earth
When did Rodinia form?
(d) Late Proterozoic (~1.1 b.y. to ~750 m.y. ago)
The dinosaurs evolved and become dominant during the _____________, between about ________ and __________ million years ago?
Mesozoic, 248, 65
The Great Dying occurred about _________ million years ago at the close of the
48, (d) Permian
What is the age of the meteorite impact at the Cretaceous/Tertiary boundary?
65 million years
Giant glaciers occupy the central portion of North America during the Pleistocene about _______ million years to ____________ years ago?
1.8, 10,000
A world-wide drop in _____________ may have contributed to the extinction of the dinosaurs by destroying their ____________ habitats.
sea level, coastal
An increase in ___________activity in western India, along with a drop in sea level, and a meteorite impact led to extinctions of many of the ________________, ~65 m.y. ago.
volcanic, dinosaurs
When did the Earth first develop an atmosphere and oceans?
Archean - ~4.0-2.5 b.y. ago
What epoch do we live in?
Holocene
In what period do primates first appear?
early Tertiary
What is Pangaea and when did it form?
second supercontinent to form on planet Earth - ~248 m.y. ago
The Earth formed from a cloud of gas and dust orbiting the Sun. During its formation and early history it was bombarded by comets and asteroids, and its surface was probably
molten
List below at least one creature the lived during the Pleistocene.
Cro-Magnon, wholly rhinoceros, mammoth, saber-tooth cat, etc.
Which of the following are possible contributors to the great extinctions that occurred at the close of the Permian?
(a) A bolide impact at Bedout High along the NW margin of Australia
(b) Eruption and formation of the Siberian Traps, and the resulting el
(a), (b), and (c) are all possible contributors to the great extinctions at the close of the Permian -
However, please be aware that some (many) scientists do not accept the evidence for (a) a
bolide impact at Bedout High
Did man evolved before or after the dinosaurs?
after
Determining the ages of rocks through their contained radioactive elements is known as ______________________ dating.
isotopic dating or geochronology
An isotope of a given element has the same atomic number as the element, but a different __________ ________________.
atomic weight
An isotope contains the same number of neutrons as the non-radioactive parent element. True or false
false
U-238 and U-235 are two naturally occurring isotopes of ____________________.
uranium
The spontaneous disintegration of the nuclei of an atom is called __________________ ___________.
radioactive decay or radioactivity
The parent of the U-238/Pb-206 isotope system is ___________.
U-238
The daughter of the U-235/Pb-207 isotope system is ___________.
Pb-207
The time that it takes a given amount of a radioactive isotope to be reduced by one-half is called the isotopes ____________.
half-life
What is the name of the constant that reflects the rate at which a radioactive isotope decays per unit of time?
decay constant
The number of parent isotopes remaining at time t is what parameter in the equation N = No(e- t).
N
What is in the equation N = No(e-t)?
decay constant
Given 100 atoms of an isotope, how many will be left after one half-life?
50
Given 100 atoms of an isotope, how many will be left after three half-lives?
12.5
What is the following equation called: t = (1/)(ln[(D/P)+1])?
age equation or fundamental age equation
What is D in the equation t = (1/)(ln[(D/P)+1])?
amount of daughter product
The amount of remaining original isotopic material is represented by what parameter in the equation t = (1/)(ln[(D/P)+1])?
P
What isotope system would you use to date a very young rock?
C-14/N-14
What isotope system would you use to date a Pleistocene tree trunk?
C-14/N-14
What isotope system would you use to date volcanic deposits containing a dinosaur?
K-40/Ar-40
Of the isotopic systems mentioned in this chapter which has the longest half-life?
Rb-87/Sr-87
Of the isotopic systems mentioned in this module which has the smallest half-life?
C-14/N-14
What kinds of rocks are found at Jack Hills, NW Australia and why are they significant?
Conglomerate. Detrital zircons were eroded, transported, and then deposited as part of the
conglomerate. A single detrital zircon was dated at 4.4 b.y. using the U-Pb method.
Minerals such as K-feldspar, biotite, and hornblende all contain the element K. What isotopic system would you use to date these minerals?
K-40/Ar-40
What isotopic system would you use to date a crystal of zircon?
U238/Pb206 or U235/Pb207
What is the oldest material dated on planet Earth, and what is its age?
Zircon, 4.4 b.y.
Where is the oldest material dated on planet Earth?
Jack Hills, NW Australia
What and where is the oldest rock dated on planet Earth? What is its age?
Acasta gneiss, NW Canada, 4.03 b.y.
What mineral and isotopic system were used to date the oldest detrital crystal and rock on planet Earth?
Zircon, U-Pb
Can you date the age of the Earth from fossils?
No, the first evidence for life on Earth does not occur until the Archean. In other words, there was no life on Earth until approximately 4.0 billion years ago. Without life there can be no fossils.