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37 Cards in this Set

  • Front
  • Back
How is geologic time split up?
Relative and absolute age dating
What is relative age dating?
Placement of age, comparatively
What is absolute age dating?
quantified data
Who is the "father of geology" by discovering relative age dating? When did he "discover" geologic time, and where did he discover it?
James Hutton
Siccar Point, Scotland
What is uniformitarianism?
The geologic processes happening today also happened in the past.
"The present is the key to the past"
What are the five rules/laws of relative dating?
Rule of Horizontality
Law of Superposition
Law of crosscutting relationships
Law of inclusion
Faunal succession
What is the rule of horizontality based upon?
flatlying layers
What is the law of superposition based on?
layers beneath layers are older
What is the law of crosscutting relationships based upon?
Faults going through layers are younger
What is the law of inclusion based on?
Inclusions are older (fragments of conglomerate are older than conglomerate)
What is faunal succession based on?
Fossils (remains of ancient organsims)
dinosaurs are older than mammoths
What are two conditions necessary to preserve fossils?
Hard parts (bones, teeth)
Rapid burial
What are trace fossils?
Indicators of ancient life, not the plant or animal itself (tracks, imprints)
What are index fossils?
Fossils that are widespread in a relatively short time span (mostly marine organisms)
What is fossil correlation?
Fossil comparison (from two areas)
What are unconformities?
a significant gap in the depositional record/sequence, "missing time"
What are the three types of unconformities?
Disconformity, Non-conformity, and angular unconformity
What is a disconformity?
Occurs between flat-lying sedimentary rocks
never deposited
significant time break (few million years)
What is a non-conformity?
Older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata
What is an angular unconformity?
An unconformity in which the older strata dip at an angle different from that of the younger beds.
What is absolute age dating?
putting numbers on "material,"
uses radioactive dating
What is different about oxygen-16 and its isotope, oxygen-18?
oxygen-16 has 8 neutrons (8+8) and oxygen 18 has 10 neutrons (8+10)
What is the relationship between parent isotopes and daughter isotopes?
parent isotopes decay to daughter isotopes at a known rate
What is the "known rate" of an isotope?
a half life
What is the half-life of carbon-14? What is its dating range? What does it decay into?
The half-life is 5,730 years. The dating range is 100-70,000 years. It decays into organic material (nitrogen).
What are the three conditions of radioactive dating?
1. Know the starting amount of a parent material, or starting ratio.

2. A closed system (minerals)

3. Choose appropriate methodology: Not too old, not too young, right ingredients
What does C14 decay into?
What are the 2 main eons? When did they begin and end?
Precambrian: 542-4500 MA
Phanerozoic- present-542 MA
What are the three eras of the Phanerozoic period?
When did the Cenozoic era begin? What are the two periods? When did our period begin
65 MA
Quaternary (1.5 MA) and tertiary
What are the three periods of the Mesozoic era?
Triassic (251 MA), Jurassic, and Cretaceous (ended 65 MA)
What are the 7 periods of the Paleozoic era?
Cambrian (542 MA), Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian (ended 251 MA)
(book) Describe the significance of the angle of repose.
The steepest slope at which material remains stable (25-40 degrees)
(book) How are earthquakes related to landslides?
An earthquake and its aftershocks can dislodge enormous volumes of rock and unconsolidated material, in the form of landslides.
(book) When the discharge of a river increases, what happens to the river's velocity?
The river's velocity also increases.
(book) What typically happens to channel width, channel depth, velocity, and discharge from the point where a stream beings to the point where it ends? Briefly explain why these changes take place.
All of the factors increase. Discharge is a function of width, depth, and velocity. If discharge increases, some other factor must also increase: (width or depth, or faster flowing water). For example, the width and/or depth of the channel will increase in order to handle additional water.
(book) What is settling velocity? What factors influence settling velocity?
Settling velocity is the speed at which a particle falls through a still fluid. The larger the particle, the more rapidly it settles toward the stream bed.