Transcript Age and Movement of Rocks

Age and Movement
of Rocks
How old is old?
• Relative Dating
a method of
determining if an
object is older or
younger than
another object.
Layer upon Layers
• Superposition
a principle that states
younger rock layers
lay on top older rock
layers.
Column of Ages
geologic column
the arrangement of rock
layers with the oldest at
the bottom.
Disturbing Forces
• Geologic Columns are
not always horizontal.
• Forces from inside the
Earth often disturb the
layers.
• There are 4 types of
disturbed rock layers.
Disturbed Rock Layers
A fault is a break in
the Earth’s crust
that moves rock
layers in different
directions.
Disturbed Rock Layers
Folding occurs
when rock layers
are bent and
buckle.
Disturbed Rock Layers
Intrusions are when
lava from inside
Earth squeezes
into cracks in rock
layers and cool.
Disturbed Rock Layers
Tilting of rock layers
occur when
internal forces
cause the rocks to
slant one direction.
Unconformities
are breaks in the geologic
column.
3 types:
a. Disconformity (missing
sedimentary rock layers)
b. Nonconformity
(sedimentary on Igneous)
c. Angular
• http://www.wwnorton.com/college/geo/ani
mations/geologic_history.htm
• http://www.wwnorton.com/college/geo/ani
mations/types_of_unconformity.htm