GEOLOGIC TIME

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GEOLOGIC TIME Concepts of Time 1. absolute
age of years since the rock formed 2. relative
age age of sedimentary rock layers in relation
to on another
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Relative Dating Techniques 1. Stratigraphic
Record i. principle of original
horizontality ii. principle of superposition
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Relative Dating Techniques 1. Stratigraphic
Record iii. unconformities (1) disconformity
erosion removes a part of otherwise undisturbed
rock (2) angular unconformity rocks below are
at an angle in relation to those
above (3) nonconformity sedimentary rocks lie
on top of igneous rocks
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Relative Dating Techniques 1. Stratigraphic
Record iv. principle of cross-cutting
relationships
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Fossils (paleontology) i. faunal
succession (1) formations
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Absolute Time Scale 1. Four major time
units i. eons ii. eras iii. periods iv. ep
ochs
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2. Determining absolute time i. radiometric
dating (1) radioactivity
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2. Determining absolute time i. radiometric
dating (2) half-life
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(3) types
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• Major assumptions
• Decay rate is constant and accurately known.
• Rock or mineral has remained a closed system.
• Daughter is solely a product of the radioactive
  decay of the parent.

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Geologic Time Scale IMPACT The earth had not
been created through a series of catastrophes,
but had instead evolved through the same types of
change that can be observed today 1. THE PRESENT
IS THE KEY TO THE PAST!
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• Earth and the neighboring planets formed on
  January 1
• Jan. and Feb. Earth differentiated a core,
  mantle, and crust
• Feb. 21, life evolved
• Spring, summer, and fall continents and oceans
  differentiated and plate tectonics started
• multicelled organisms appeared on October 25
• in late November plants and animals became
  abundant on land
• on December 15 the dinosaurs appeared
• by December 25 they became extinct
• we arrived on December 31 at 1120 p.m.
• and less than a second and a half before midnight
  on that same day the Industrial Revolution began