Section 2
Relative Dating: Which
Came First?
•Write a news article from the perspective of a
geologist
•Include all of the key terms from this week
•Your story must make sense
•Be creative and have fun!
Relative Dating
• Determining the age
and order of
particular events or
objects.
http://encyclopedia.laborlawtalk.com/wiki/images/thumb/1/14/250px-Grand_Canyon_geologic_column.jpeg
Superposition
• Younger rocks lie
above older rocks in
undisturbed
sequences.
http://earth.geol.ksu.edu/liu/g100/figures/15_superposition.jpg
The Geologic Column
• An ideal sequence
of rock layers that
contain all the
known fossils and
rock formations on
earth, arranged from
oldest to youngest.
http://en.wikipedia.org/wiki/User:Maveric149/images/Idaho
http://www.nps.gov/care/resources/admin%20history/images/fig3.jpg
Disturbed Rock Layers
http://scamp.wr.usgs.gov/scamp/photo/aug88p07JKN-26M.jpg
http://www.utdallas.edu/dept/sci_ed/torch/bb00_geo-al_files/image018.jpg
http://www.stmarys.ca/conted/webcourses/GE
O/GEO99/pubigneous/intrusion.gif
http://www.nps.gov/care/graphics/wtrpkt1.gif
The Missing Piece
• Unconformity-a surface missing
part of geologic column.
– Nondeposition
– Erosion
• Disconformities
• Nonconformities
• Angular Unconformities