Historical Geology prep for quiz ch 3/4 Flashcards Table View


What is geology's most important contribution to human knowledge?
recognition of immensity of geologic time
the science that deals with determining the ages of rocks
the actual age. quantifying the age of the rock or mineral in years
absolute age
determining which rocks are older and which are younger
relative age
What are the divisions of geologic time scale from longest to shortest?
Eon -> Era -> Period -> Epoch -> Age -> Chron

What are the eons?
Precambrian=Hadean, Archean, Proterozoic, and Phanerozoic (evident life)
What are the eras in the Phanerozoic eon?
Paleozoic (evident life), Mesozoic (middle life), and Cenozoic (recent life)
What is the nemonic for the Phanerozoic periods and epochs of the geologic timescale?
Camels often sit down carefully, perhaps their joints creak, perhaps early oiling might prevent permanent rheumatism
Divisions of Stratigraphy (Chronostratigraphic units) correspond to _____________ _____
geochronologic units
Erthem =
System =
series =
stage =
chronozone =
most rocks initially were identified in ______ and now scientists have discovered similar rocks of same age in other parts of the world

who named the Cambrian period?
Adam Sedgwick
What are some of the early attempts to estimate the age of Earth and calibrate the time scale?
1. biblical geneology
2. mollusc evolution
3. accumulation of sedimentary strata
4. salinity of the ocean
5. Lord kelvin, cooling model
What are the only North American naming of periods that's not from Europe?
Pennsylvanian and Mississippian
smallest particle of matter that can exist as a chemical element
what does the structure of the atom consist of?
nucleus composed of protons and neutrons, electrons, and various subatomic particles
number of protons in the nucleus of that atom
atomic number of an atom

the sum of the number of protons plus neutrons
mass number
the mass number may vary for an element, because of a _______ _____ __ ________
differing number of neutrons
elements with same atomic number, but different atomic mass number (different neutron numbers_
isotopes undergo ________ ______
radioactive decay
during ______ ______, an atom's nucleus sheds two protons and two neutrons in a packet that scientists call an alpha particle resulting in a mass number of minus 4 and atomic weight of minus 2
alpha decay
when an electron is released because a neutron has changed into a proton and electron. Atomic number increases by 1
beta decay

occurs because the nucleus is at too high an energy. the nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a ______ particle. the number of protons (and neutrons) in the nucleus does not change in this process, so the parent and daughter atoms are the same chemical element
gamma decay
employs rate of natural, spontaneous breakdown of nuclear structure of atoms
daughter product + particle expelled
parent nuclide
rate of nuclear decay is ____ of radioactive isotopes
crystallization of minerals locks in an original quantity of ____________ _____
radioactive atoms
the rate of decay (is/is not) affected by changes in pressure, temperature, or other chemicals
is not
span of time needed for one half of original atom to decay to daughter product = constant of each system
half- life
device used to measure minute amounts of isotopes
mass spectrometer

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