4 Principles of Relative Dating
The process of placing events in the order that they occurred in the earth.
Superposition
Original
Horizontality
Cross-Cutting
Relationship
Unconformity
means that
means that
means that
means that
the oldest rocks
are located
on the
Sedimentary rock layers
always begin
in a
HORIZONTAL POSITION
ANYTHING
a GAP forms
in a series of rock layers
BOTTOM
of
Horizon = parallel to the ground
undisturbed rock layers
that
CUTS across rock layers
is
YOUNGER
than
the rock layers it cuts through
due to
EROSION
Younger Rock
Younger Rock Layers
OLDEST Rocks
Older Rock Layers
http://www.geol.umd.edu/~jmerck/geol100/images/24/superposition.jpg
jhaugh: X Drive/ Graphic Org 2011 Earth Science Geologic Time
Igneous
Intrusions
FAULTS or
CUT through
rock layers
and are
CRACKS
CUT through
rock layers
and are
YOUNGER
YOUNGER
J. Hoffmann Notes/ J. Haugh Visuals/ Google Images/ I Drive Earth Science 2012
Older Rock
Unconformity