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?
In the past there were (more or less) atoms of radioactive Uranium?
Therefore, there was (more or less) heat produced in the crust in the past:
Which of the following represents the longest time period
The Paleozoic does not include the
The _________ was an era dominated by the dinosaurs
The boundaries between _______ seem to coincide with major changes in the life forms present on Earth.
Radiometric age is often referred to as __________ age.
The principal of original horizontality states that ________ .
An undeformed sedimentary layer is __________ than the layer above and _______ than the layer below.
Fossils are most common in which rock types?
The study of faunal succession allows ___________ .
A disconformity is ___________ .
What is the name for an erosion surface that separates two sets of sedimentary layers with non-parallel bedding planes?
Which of the following is used by geologists to determine the relative ages in a rock sequence?
Which of the following could be used to tell if a rock layer was right side up or up side down__________ .
Radiometric dating is least useful for ___________ rocks.
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?
A Potassium-Argon (K-Ar) age measures _________ .
Which of the following radioactive isotopes is most useful for dating a very young sample (<20,000 years) of wood?
A stratigraphic sequence is a vertical set of strate
We cannot accurately measure time in years with stratigraphy for several reasons. Which of the following is false.
Which of the following will not make a fossil?
The most common fossils in rocks of the last 500 million years are _______
Who is credited with developing the principle of faunal succession?
A nonconformity is _________ .
What is the name for an erosion surface that separates two sets of sedimentary layers with non-parallel bedding planes?
Which of the following units is the youngest?
Which of the following units is the oldest?
Which of the following happened most recently?
Which of the following statements is true?
George Geologist finds that unit F contains eroded pieces of unit G. Which of the following statements is true?
The horizontal line labeled X-X' is a(n) ________ .
Which of the following statements is false?
Which of the following occurred most recently?
The age estimate for point A in the diagram above is ______ million years
The age estimate for point B in the diagram above is ______ million years
The age estimate for point C in the diagram above is ______ million years
The age estimate for point D in the diagram above is ______ million years
The age estimate for point E in the diagram above is ______ million years
Most periods in the geologic time scale are named for _______.
What scientific avenue of investigation gave scientists the best estimate of the age of the Earth?
Radiometric dating is possible if a rock contains a measurable amount of ________ .
Radiometric dating is least useful for dating _________ rocks.
Which of the following statements regarding radiometric dating is false?
Which of the following radioactive isotopes has the longest half-life?
Which of the following radioactive isotopes has the shortest half-life?
Uranium-238 decays to which of the following daughter isotopes?
Which of the following isotopes is most useful for dating very young wood and charcoal?
The radon environmental hazard is associated with the radioactive decay of ______ .
Human beings evolved during which geologic era?
Mammals became abundant during the ________Era?
Large reptiles became abundant during the ________Era?
Land plants appeared during the ________Era?