Geologic time
The age estimate for point A in the diagram above is ______ million years
1.6
A rock formed with 1,000 atoms of a radioactive parent element, but only contains 250 radioactive parent atoms today. If the half-life is 1,000,000 years, how old is the rock?
2,000,000 years
The age estimate for point C in the diagram above is ______ million years
245
The age estimate for point E in the diagram above is ______ million years
2500
Atoms of AA decay to atoms of BB with a half-life of 100,000 years. If there are 20,000 atoms of AA to begin with (and 0 atoms of BB), how long will it take for there to be 2,500 atoms of AA?
300,000 years
The age estimate for point D in the diagram above is ______ million years
570
The age estimate for point B in the diagram above is ______ million years
65
Which of the following units is the youngest?
A (above x)
Human beings evolved during which geologic era?
Cenozoic
Mammals became abundant during the ________Era?
Cenozoic
Which of the following units is the oldest?
D (below x)
The Paleozoic does not include the
Jurassic
The _________ was an era dominated by the dinosaurs
Mesoic
Large reptiles became abundant during the ________Era?
Mesozoic
In the past there were (more or less) atoms of radioactive Uranium?
More
Therefore, there was (more or less) heat produced in the crust in the past:
More
Land plants appeared during the ________Era?
Paleozoic
Which of the following represents the longest time period
Precambrian
Which of the following statements regarding radiometric dating is false?
Sedimentary rocks can be dated more easily than igneous rocks
Who is credited with developing the principle of faunal succession?
William "Strata" Smith
A nonconformity is _________
a gap in the geologic record bounded below by metamorphic or igneous rocks and bounded above by sedimentary rocks
Radiometric age is often referred to as __________ age
absolute
A disconformity is ___________
an erosional surface between horizontal sedimentary rocks
The horizontal line labeled X-X' is a(n) ________
angular unconformity
What is the name for an erosion surface that separates two sets of sedimentary layers with non-parallel bedding planes?
angular unconformity
Radiometric dating is possible if a rock contains a measurable amount of ________ .
both parent and daughter isotopes
Which of the following isotopes is most useful for dating very young wood and charcoal?
carbon-14
Which of the following radioactive isotopes has the shortest half-life?
carbon-14
Which of the following radioactive isotopes is most useful for dating a very young sample (<20,000 years) of wood
carbon-14
Which of the following will not make a fossil?
decomposed organic material
Which of the following occurred most recently?
deposition of unit A
Which of the following happened most recently?
deposition of unit B (before x)
The boundaries between _______ seem to coincide with major changes in the life forms present on Earth.
eras
Most periods in the geologic time scale are named for _______
geographic localities
The most common fossils in rocks of the last 500 million years are _______
invertebrate shells
Uranium-238 decays to which of the following daughter isotopes?
lead-206
We cannot accurately measure time in years with stratigraphy for several reasons. Which of the following is false
many sedimentary rocks contain fossils that have not been identified
The study of faunal succession allows ___________
matching of similarly-aged rocks from different outcrops
An undeformed sedimentary layer is __________ than the layer above and _______ than the layer below
older --- younger
What scientific avenue of investigation gave scientists the best estimate of the age of the Earth?
radiometric dating
Fossils are most common in which rock types?
sedimentary
Radiometric dating is least useful for ___________ rocks
sedimentary
Radiometric dating is least useful for dating _________ rocks.
sedimentary
The principal of original horizontality states that ________
sediments are deposited as essentially horizontal layers
Which of the following is used by geologists to determine the relative ages in a rock sequence?
stratigraphy fossils cross-cutting relationships
Which of the following could be used to tell if a rock layer was right side up or up side down__________
symmetrical ripple marks
Which of the following statements is true?
the relative ages of the granite and unit B cannot be determined from the information given
A Potassium-Argon (K-Ar) age measures _________
the time since last cooling below the gas retention temperature - Argon is the gas
George Geologist finds that unit F contains eroded pieces of unit G. Which of the following statements is true?
unit B is younger than the granite
Which of the following statements is false?
unit C is younger than unit A
The radon environmental hazard is associated with the radioactive decay of ______ .
uranium-238
Which of the following radioactive isotopes has the longest half-life?
uranium-238
A stratigraphic sequence is a vertical set of strate
used as a chronological record of the geologic history of a region