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NATS 1003
Syllabus
Topic Outlines

Topic 10   Geologic Time

Primary goals

• Describe geologic history from relative geologic features.
• Arrange layers and events in a geologic cross-section in relative time order.
• Understand the general mechanism of absolute dating using radiometric decay.

Topics

10.1  Introduction  

• Terms: relative dating; absolute dating

10.2  Relative dating 

• Rule: Sedimentary layers are deposited/formed horizontally

• Rule: In undisturbed sedimentary rock layers, older stuff is below younger stuff

• Rule: Geologic features that cut across rocks must have occurred after the rocks were formed

• Rule: Fragments of one rock contained in another rock tell us that the included rock is older

• Analytical: Be able to apply the relative dating rules to rock cross-sections

10.3  Unconformities  

• Terms: unconformity; disconformity; angular unconformity; nonconformity

• Story: How could a disconformity have occurred?

• Story: How could an angular unconformity have occurred?

• Story: How could a nonconformity have occurred?

• Analytical: Be able to recognize the type of unconformity on a rock cross-section

10.4  Absolute dating  

• Terms: radioactive decay; half-life; parent isotope; daughter isotope

• Explanation: How do geologists use radioactive decay to determine the age of a rock?

10.5  Correlation  

• Explanation: How are rock types used to correlate rock sequences?

• Explanation: How are index fossils used to correlate rock sequences?

• Explanation: How are key beds used to correlate rock sequences?

10.6  Geologic Time Scale

Resources for students

Entire course

• Course lecture notes from:
  --Prof. Nelson (detailed)
  --U of Illinois lecture 1

• Videos
  --15 min
  

Links for further interest

10.2  Relative dating

• Law of original horizontalilty video    1 min

• Example in Colorado river   2 min

• Example in Arizona   1 min

10.3  Unconformities

• Grand Canyon video   1min
  --Another video of Grand Canyon   2 min

10.4  Absolute dating

• basic description and application

10.5  Geologic time scale

• Move along time scale 63 m    6 min
• U. of California, Berkeley Museum of Paleontology (Lots of good stuff!! Browse!!)