Class # ___: Absolute and Relative Rock Dating
Name _______________________ Core 1 2 3
Activity 1: Read Chapter 11.2 and take book notes in your Lab journal for pages 312 – 318 & Q’s 1-3
Activity 2: Lecture Notes 1. What are relative and absolute locations?
Absolute Location
Relative Location
2 Ways to Date Rocks:
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Absolute Dating
Gives us the t________________ “age” of a fossil or rock
All you need _________________________.
Mainly o__________________________ tissue or
i____________________ crystals
Measures the amount of
_________________________________ that have “decayed”
to figure out age
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Relative Dating
Places events in geologic history in the proper
order r_____________________________ to one another.
The basis for the g_______________________________ time
scale
Does n___________ provide a true “age”
P_______________ for Relative Dating:
Principles for Relative Dating:
Law of S_______________________rposition : In any undisturbed sequence of strata:
• the oldest layer is at the bottom
• the youngest layer is at the top.
The Cross-cutting Law
• Any feature that c_______________ a____________________ a body of sediment or rock is y
body of sediment or rock that it cuts across.
than the
Law of Inclusions - Rocks e______________________________ in other rocks are o___________ than those rocks they are
embedded in.
Law of Original Horizontality (and Lateral continuity) – layers of sediments are originally deposited
h____________________________
BUT Stuff can happen like: E _______________
Types of Discomformities
Angular conformity:
younger sediments rest
upon the eroded surface
of tilted or folded older
rocks.
E_________________ F_______________ D_________________
Disconformity: contact
between younger and
older beds is marked by a
visible, irregular or uneven
erosional surface.
Nonconformity: develops
between sedimentary
rock and older igneous or
metamorphic rock that
has been exposed to
erosion.
Paraconformity: beds above
and below the unconformity
are parallel and no erosional
surface is evident; but can be
recognized based on the gap
in the rock record
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Activity 3: Relative Dating Exercise
A  The Oldest
T  The Youngest
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