Determining Relative Age
Chapter 8 section 1
Objectives
• Explain Hutton’s principle of
________________________________.
• Define ___________________________.
• Describe _______types of unconformities.
• Explain the laws of __________________ &
_______________________________.
Uniformitarianism
• James Hutton proposed that by studying the ________________,
people can learn about the ________________.
• ______________________________________- current geologic
processes such as volcanism & erosion are the same processes
that worked long ago to shape our Earth.
• Geologists agree with Hutton that the processes are the same, but
_______________________
______________________________________.
• Hutton’s work led scientists to question the age of the Earth
(_______________ years).
Relative Age
• ___________________________- the age of something in
relation to something else.
• Relative age indicates that one rock layer is older or
younger than another, but does not indicate the rock’s
_______________ __________________.
• Although many types of rock form layers, scientists
typically study ______________ _______________ rock.
Law of Superposition
• _________________________________- in undeformed
sedimentary rock, a layer of rock is older than the layers
above it and younger than the layers below it
Unconformities
• __________________________- a break in the geologic record—
usually caused by erosion
• 3 types
– _________________________- stratified rock on top of unstratified rock
– _________________________- boundary between a set of tilted layers
and a set of horizontal layers
– _________________________- boundary between horizontal layers of old
rock & younger layers deposited upon an eroded area
Crosscutting Relationships
• _________________- a break or crack in Earth’s crust
along which rocks shift
• _________________- mass of igneous rock formed when
magma is injected into rock then cools & solidifies
• _________________________________- a fault or
igneous intrusion is younger than the rock layers that it
cuts through