Geology 1023

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Geology 1023

• Correlations

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Correlations

• Outcrop is not continuous
• We need to be able to compare and contrast rocks
  at different locations i.e., correlate
• Various approaches but all involved identifying
  and recording the rocks and their structures at
  each locality

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Contacts

• Conformable
• abrupt
• gradational
• Unconformable
• angular unconformity
• non-conformity
• disconformity

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Stratigraphic column

• Record of rocks present at any given location
• Rectangular column with unit thickness shown by
  proportional division and composition shown by
  patterns

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Simulated column

• Rocks at back of lab
• Given thicknesses and lithologies
• Write out some descriptions
• Make a column

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Add scale, using an arbitrary zero point.
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First unit is 2 m of shale (2 columns wide)
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Next unit is 2 m of sandy siltstone (2.5 columns
wide)
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Next unit is 10 m of conglomerate (4 columns wide)
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and so on!
Once column is complete, subdivide into
formations.
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Physical correlation

• Use the photo to walk out the outcrop
• Determine the type of fold
• Correlate different positions
• Determine the ages

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Correlations

• Once columns are prepared then the geology at
  each location can be compared and correlated.

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Geophysical properties

• One can correlate using geophysical properties
• Fig. 8 (p. 11) shows a real case

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And so on...
But whats going on here?
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Questions?
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Reminder!Lab test next week!