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How old is old?

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Absolute Age• Scientists can use several methods to determine absolute age:• Radioactive decay• Radiocarbon dating• Tree ring dating• Ice cores• Varves

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Radioactive decay• The emission of radioactive particles and the resulting change into other isotopes over time is called radioactive decay.• This decay happens at a constant rate, so it can be used to determine the age of the minerals in a rock.• For sedimentary rocks, scientists date layers of igneous rock or volcanic ash above and below the sedimentary layers

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Radiocarbon dating• This is used to determine the age of carbon material, or things that were alive.• The amount of carbon decreases over time which allows scientists to determine how long ago the object died.

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Dendrochronology – Tree Ring dating

• Every year, a tree produces two rings (a darkcolored and a lightcolored ring).  • Counting the rings allows scientists to know how old the tree was when it died.  Used in combination with carbondating, this can help determine the age of a tree.

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Ice Cores• Ice cores contain a record of past environmental conditions in annual layers of snow. • Geologists use icecores to study glacial cycles.

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Varves• Bands of alternating light and darkcolored sediments of sand, clay, and silt are called varves.• Using varved cores, scientists can date cycles of glacial sedimentation over periods as long as 120,000 years.

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Discussion Question 2• How are ice cores, varves and trees rings similar?  How are they different?  Be specific.  Your answer should be 50 – 75 words in length.

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questions

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If you get your question right...

1  Erase one 1 point from all other teams.

2   Double your score.

3  Add two points to your score.

4 Erase two points from one other random team.

5  Randomly have a player from the winning team go to the losing team.

6   The team with the least points must collectively do 10 pushups.

Game rules: 1. Click to the die.2. Answer a question.3.  If you get the question right, you get the number of points on the die and the action from the list.

Bazinga

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Attachments

review game questions.xlsx

Sheet1

Carbon 14 is used for which kind of dating?absolute dating

In what kind of rock would you find fossils?sedimentary

What do index fossils help us determine?age of rock layers

The law of superposition states….the oldest rock layers are at the bottom, youngest at the top

The law of crosscutting relationships states…a fault is younger than the rock layers that it goes through

The principle of uniformitarianism statesthe same processes that are occurring today also occurred in the past.

The principle of inclusions statesthe inclusion is older than the rock it is included in.

The principle of original horizontality statessedimentary rock forms in horizontal layers

which is older, the rock layer or the fault cutting through it?rock layer

what makes a fossil a good index fossillived for a short time, but in a large area

What does a scientist use to determine age when using dendrochronology?tree rings

A sedimentary deposit that forms in glacial lakesvarve

A sample pulled from a glacier that holds clues to the ancient atmosphereice core

Using rock layers and/or fossils from one area and comparing them to another area to determine agecorrelation

a gap in the rock layer from erosionunconformity

In what period did the first birds show up?Jurassic

During which period were sharks abundant?Coniferous/Mississippian

In what Era did the first terrestrial animals show up?Paleozoic

During which time frame were fossils rare?Precambrian

In what period did the largest mass extinction occur?Permian

During which epoch did the northern glaciation occur?Pleistocene

Sheet2

Sheet3

SMART Notebook

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