Unit 6 Day 2 Notes
Age Dating
Age Dating
SOL 10
c.
and
dating have different applications but can be used
to determine the age of rocks and structures.
Objective
2. Define
and
Relative-Age Dating of Rocks
Relative age dating places the ages of rocks and the
events that formed them in order, but without
, by
layer to another

The Colorado River has cut through rock
years!) to form the
3. Identify how fossils, superposition, and crosscutting
relations are used to determine the
of
rocks.
4. Differentiate between
and
5. Identify how
is used to
determine the
of rocks.
Age Dating
As late as the turn of the nineteenth century the
.
Principle of
states
that
rocks are
deposited in nearly horizontal layers
majority of the world believed that Earth was only about
.
This age was primarily determined by using
and
historical records.

, a Scottish geologist is noted for
his observations of Earth’s landscapes and discovering
that our planet is MUCH
than 6,000 years Principle of
states that
in an undisturbed sequence the oldest rocks are on the
bottom then
than the one beneath

exist when the
layers are disturbed by an
or
.
The
than
the rock it cuts

states that the processes
have been
in
the same way since the Earth formed


is a
record caused by
or
.
8

forms when a horizontal
sedimentary rock layer is

decays into Pb-206 over a
specific span of time

sedimentary rocks
is the
process used to determine the

forms when a sedimentary
of a rock or fossil by determining the ratio of
rock layer is
parent nuclei to daughter nuclei within a sample

is the period of time it takes for a
Correlation is the
of outcrops radioactive isotope (parent) to
from one geographic region to another

a radioactive isotope commonly
used for dating many

is commonly used to determine
the age of materials that are of

dating is accurate for up to
Other Ways to Determine Age
Naturally occurring materials such as
,
and
can also be used to determine the age of an
object
Absolute-Age Dating

allows scientists to
of a
determine the
rock, fossil, or other object

can be
to
determine the age and
of a particular area

are alternating bands of dark and light
colored sediments that determine the age of
layers
Distinctive sediment layers mark catastrophic events
such as
and
Scientists have devised a method for dating very old
objects using the decay rate of

is the emission of
radioactive particles and the resulting
over time
The original element is called the “
and the new element is called the “
”
”
Key Beds are time markers of such events that are
used to correlate rock layers across large areas
VA SOL
9