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Geologic Time
Chapter 211-213
Geologic Time
bull Two frames of referencendashRELATIVE AGE DATING
bull Places events in order according to their positions in the rock record
ndash ABSOLUTE AGE DATINGbull Specific ages of rock units etc
bull Given as Years Before Present
Geologic Time Scale
bull RELATIVE SCALE with ABSOLUTE AGES added
bull 1048649Modified as new information becomes available
Divided into (p 591)
bullEons
bullEras
bullPeriods
bullEpochs
212 Relative Age Dating
bull Uniformitarianismndash ldquopresent is the key to the pastrdquo
ndash James Hutton 1788bull Beginning of ldquoMODERN GEOLOGYrdquo
ndash Charles Lyell
ndash Not immediately embraced by scientists of the day
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Geologic Time
bull Two frames of referencendashRELATIVE AGE DATING
bull Places events in order according to their positions in the rock record
ndash ABSOLUTE AGE DATINGbull Specific ages of rock units etc
bull Given as Years Before Present
Geologic Time Scale
bull RELATIVE SCALE with ABSOLUTE AGES added
bull 1048649Modified as new information becomes available
Divided into (p 591)
bullEons
bullEras
bullPeriods
bullEpochs
212 Relative Age Dating
bull Uniformitarianismndash ldquopresent is the key to the pastrdquo
ndash James Hutton 1788bull Beginning of ldquoMODERN GEOLOGYrdquo
ndash Charles Lyell
ndash Not immediately embraced by scientists of the day
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Geologic Time Scale
bull RELATIVE SCALE with ABSOLUTE AGES added
bull 1048649Modified as new information becomes available
Divided into (p 591)
bullEons
bullEras
bullPeriods
bullEpochs
212 Relative Age Dating
bull Uniformitarianismndash ldquopresent is the key to the pastrdquo
ndash James Hutton 1788bull Beginning of ldquoMODERN GEOLOGYrdquo
ndash Charles Lyell
ndash Not immediately embraced by scientists of the day
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Divided into (p 591)
bullEons
bullEras
bullPeriods
bullEpochs
212 Relative Age Dating
bull Uniformitarianismndash ldquopresent is the key to the pastrdquo
ndash James Hutton 1788bull Beginning of ldquoMODERN GEOLOGYrdquo
ndash Charles Lyell
ndash Not immediately embraced by scientists of the day
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
212 Relative Age Dating
bull Uniformitarianismndash ldquopresent is the key to the pastrdquo
ndash James Hutton 1788bull Beginning of ldquoMODERN GEOLOGYrdquo
ndash Charles Lyell
ndash Not immediately embraced by scientists of the day
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Six Principlesndash Principle1 Superposition
bull Oldest layer on bottom youngest on top
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Marine Transgression
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Marine Regression
sea regressing
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Principle 2 Original Horizontalityndash Sediments originally deposited horizontally
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Principle 3 Lateral Continuityndash Layer continues equally in all directions
eventually ldquopinchesrdquo out
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Principle 4 Cross-Cutting Relationshipsndash Igneous
intrusion or fault is younger than the rock it cuts across
fault cuts acrossSedimentary layers
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Igneous dikecuts acrossgranite
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Principle 5 Inclusionsndash Rock
fragments in a layer are older than the rock itself
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Relative Age Dating
bull Principle 6 Fossil Successionndash Fossil assemblages succeed one another
in a regular and predictable orderndash William Smith English surveyor 1815ndash Index fossils (guide fossils)
bull Geographically widespreadbull Existed for short geologic timebull Easily identifiedbull Abundant
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Unconformities
bull Surfaces which represent geologic time not represented in the rock record
bull Hiatus Interval of time not represented
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Types of Unconformities
bull Disconformity ndash Surface of
erosion or non-deposition between beds which are parallel to one another
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
MississippianMississippian
Jurassic
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Types of Unconformities
bull Angular Unconformity Erosional surface on tilted or folded strata over which younger strata are deposited
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Types of Unconformities
Nonconformityndash Erosional
surface cut into igneous or metamorphic rocks overlain by sedimentary rocks
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
Absolute Age Dating
bull A rock layer or event can be assigned a number years before present with an error factor
bull Radiometric datingndash Radioactive elements spontaneously
decay to a more stable element
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
bull Radiometric datingbull Unstable radioactive elements or isotopesbull (ldquoparentsrdquo) change over time into stablebull products (ldquodaughtersrdquo)bull ndash PARENT rarr DAUGHTERbull Half-life Time for frac12 of parent to change tobull daughterbull Half-life is UNIQUE and CONSTANT
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
bull Radiometric dating
bull Types of Decayndash Alpha ndash lose a He nucleus (2p + 2n)ndash Beta ndash lost an e-ndash Electron capture ndash gain an e-
Absolute Age Dating
