Aim: How do we determine the relative age of rocks?

Do Now:1. What have we already learned about

rock age in the last unit (Think about the laws pertaining to strata)?

2. What is contact metamorphism?3. Take out your review book, a piece of

paper, and a PENCIL

HW: R&H 278-282 A&E 1-20

4/5/11

Exceptions to Superposition Overturned folds or

thrust faults can upset the law of superposition. (The oldest rock layers are no longer on the bottom).

Rocks layers usually fold before they fault

New TermsInclusion – a body of older

rock inside an intrusion which did not melt when the intrusion formed

Cross Cutting –Cross cuts are always younger then the rock they cut through. (Faults, Intrusions, Veins)

Unconformities - a layer of eroded rock which shows that there are rocks missing from the record

Correlation of Rock Layers (p.281) Lateral Continuity –

sediments are initially deposited in a horizontal fashion extending out in all directions

Exposed bedrock is called an outcrop

Index Fossil – a fossil used to help date rock age. Must have existed over a wide area for a short period of time

Volcanic Ash and Meteorite Deposits – can be used to date rock age based on the same requirements as index fossils

Aim: Using the ESRT to interpret Geologic History

Do Now:1. Complete Question 1 on your

worksheet.2. What is an inclusion3. What are the two aspects of a

good index fossil

HW: R&H 284-286 A&E 21-36

4/6/11

Aim: How do we give rocks Absolute Ages?

Do Now:1. Finish questions

on the ESRT Practice Worksheet from yesterday.

HW: R&H 288-290 A&E 37-46

4/7/11

Radioactive Decay An element is any

substance consisting of atoms which are chemically alike

Elements can have heavier versions called isotopes

Isotopes are unstable and decay into different elements overtime

Half Life The time it takes

for half the atoms in an isotope to turn into a stable element

Different isotopes have different half lives

Radioactive Dating You can use the ratio

of original isotope to disintegration product to estimate the absolute age of a rock

Rocks with shorter half lives are used to date more recent events and vice versa

Carbon 14 can date fossils and rocks up to 50,000 years old

Aim: How have Earth’s environment and Life on Earth changed over time?

Do Now:1. Half Life Worksheet2. Can anything effect

the rate of a half life?

3. Take out review books

HW: R&H 291-295 A&E 47-52 (Lab if Lab Day)

Crash Course in Evolution The first life on Earth occurred about 4 billion years ago Because of chemical mutations, sexual reproduction, and a many

other reasons all life has variation The environment acts on these variations and selects organisms

with the best traits for that environment (Natural Selection – THERE IS NO PURPOSE TO EVOLUTION)

Over time this selection changes the way a given set of organisms will look and behave and this selection can create new types of organisms.

Lets Look at the ESRT to see how the Earth and Life have changed over time

Some things to keep in mind: Fossils give us evidence about Earth’s past

environment Plate Tectonics have caused changes in

Earth’s environment globally and locally Evolution is rapid after an extinction event