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GEOL 3000 Geologic Maps. Determining the Relative and Absolute Age of Map Units. Relative Age Dating - Superposition. Up isn’t always Younging. Up Indicators. Graded Bedding. Pillowed Lavas. Amygdaloidal Zones in Lavas. Cross-bedding. Ripple Marks.
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GEOL 3000Geologic Maps Determining the Relative and Absolute Age of Map Units
Up Indicators Graded Bedding Pillowed Lavas Amygdaloidal Zones in Lavas Cross-bedding Ripple Marks
Advanced Transgression Regression
Principles of Faunal Successionand Faunal Assemblage Index Fossils - Widespread distribution - Restricted, known time of existence - Common to many environments
The Jordan Sandstone Unconformity Missing Fossils
Gaps in the Geological RecordUnconformities Siccar Point, Scotland “The mind seemed to grow giddy looking so far into the abyss of time” John Playfair – Illustrations of Huttonian Theory (1809)
Creating Unconformities Nonconformity Grand Canyon Stratigraphy Angular Unconformity Disconformity
Unconformities or Pinch-outs?
Regional Correlation of UnitsPiecing the Rock Record Together
Relative Time for Intrusive Igneous RocksPrinciple of Cross-cutting Relationships
Global Time MarkersMeteor Impacts K-T Boundary mudstone-impact layer coal K-T impact site
The 1.875 Ga Sudbury Impact The First Major Extinction Event ??
Radioactive Decay Half-life Zircon ZrSiO4 U substitutes for Zr, but Pb does not.
Rb-Sr Dating of a Granite 87Rb 87Sr; 86Sr is stable Rb – chemically substitutes for K Sr – chemically substitutes for Ca Isochron t=2 t=1 87Sr/86Sr Metamorphism at t=1 87Sr/86Sr°(m) t=0 87Sr/86Sr° 87Rb/86Sr Ca-plagioclase Granite whole rock K-feldspar Biotite (K-rich)