Earth’s Age + Evidence
WARM UP• Update your Table of Contents for today’s
activities• Get your data folder off the front desk• Complete Types of Rock Review section
at the top of your note guide
Date Session#
Activity Page#
9/13 7 Earth’s Age & Evidence Note guide 14
Law of Superposition Practice 15
Review: Types of Rock
Which one?
- Created from the deposition of loose material accumulating into layers and being pressed together over time
Review: Types of Rock
Which one?
-The result of the transformation of other rocks into a new form
Review: Types of Rock
Which one?
- Created when molten rock (magma) cools and hardens
Notes Tips and Tricks
• Anything in yellow you MUST write on your note guide
• Pictures and diagrams are great things to also draw to help you remember vocab and ideas!
• Underlined or bold words that are underlined or bold in PowerPoint BECAUSE THEY ARE IMPORTANT!
How old is the Earth?
Earth is around 4.6 BILLION years old.
BIG QUESTION:
HOW DO WE KNOW HOW OLD THE
EARTH IS?
BIG ANSWER:
Everything coming up provides an
answer to the BIG QUESTION!
Law of Superposition
• Law of Superposition– •Under normal conditions, the layers of sediment get older the deeper you get
Examples of Law of Superposition
• Just like a layered cake…you put the bottom layer down first,
so it is the “oldest” and
you fill in each layer on
top of it! What examples
can you come up with?
Draw your own picture
illustrate the concept!
We Have a Problem…
• There are several things can mess up the Law of Superposition called unconformities
Types of unconformities:
1 – intrusion
2 – overturning
3 - faults
Unconformity• Unconformity-
•A break or an irregularity in the geologic time sequence due to a geologic event.
•“Missing Information”
1. Intrusion• A intrusion is igneous rock that cuts
through layers of sedimentary rock. The intrusion is younger than any other rock layer it cuts through.
intrusion
2. Overturning• Overturning is when rock layers
are folded due to gravity, erosion, or shifts in Earth’s crust
3. Faults• Faults are cracks, fractures or shifts in
Earth’s crust
Fault
Law of Superposition Practice
Which type of unconformity do you see in the diagram?
Can you put the layers in order from oldest to youngest?
Law of Superposition Practice
Which types of unconformity do you see in the diagram?
Can you put the layers in order from youngest to oldest?
What is This?
Fossils• Fossil – traces or remains of living
things from long ago that help sort out the sedimentary rock record
• Index Fossils – fossils that are used as a “reference” to date other fossils
Types of Fossils
• BrainPOP Video
Fossil Samples
• Decide which type of fossil each sample is:
Homework• Vocab Set 2 – Days 1 & 2
• Other Ways of Determining Reading Comprehension with Questions (if not finished in
class)
Warm-Up• Update your Table of Contents• Get your vocabulary cards out to be checked
(remember I’m checking days 1 & 2)• Tape “Other Ways of Determining Age” into
page 16 of your Interactive NotebookDate Session
#Activity Page
#
9/17 8 “Other Ways of Determining Age” Reading Comprehension
16
Determining Age Note Guide 17
Silent Stations Skill Practice Answer Sheet 18
Review
• What were some things we talked about last class that help us determine how old
Earth really is?
Relative Age• Relative Age - the age of an event or
object in relation to other events or objects
–Use words like older, younger, around the same time, etc…
Time for more specific evidence…
Absolute Age• Absolute Age - The actual age of an
event or object– Use techniques to figure out actual age
• Radioactive dating, carbon dating
Lived:
1 million years ago
2 million years ago
3 million years ago
4 million years ago
Types of Dating• Radioactive (Radiometric) Dating – If you
know how much radioactive material was initially present in the sample and you know the half-life of the material, you can calculate the age of the sample.
• Carbon Dating – Using the amount of carbon in fossil remains to determine the age (sample must have been alive to use carbon dating)
What’s a “half-life?”• Half-life – the length
of time it takes for half of the atoms in a sample of a radioactive to change
• This break down occurs at a constant rate depending on the substance
Types of Dating
• BrainPOP Video – Carbon Dating
• Half-life Practice
Questions??
“SILENT STATIONS”
Be sure to tape the station guide into your notebook!
Homework•Vocab Set 2 – Day 3