3-28-12How do we determine a sequence of events

for rock layers? Do Now:1. What is original horizontality,

superposition, and uniformitarianism?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

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 - buried erosional surfaces which show that there are rocks missing (or a gap) 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 (rapidly deposited over a large area.)

3-30-12Aim: How do we correlate rock layers?

Do Now:1. What is an inclusion?2. What are the two aspects of a good

index fossil?3. Why are volcanic ash and meteorite

deposits good time markers?

HW: Finish Matching Rock Layers Lab.

4-3-12What is the geologic history of NYS?

• Do Now:• 1. How do we know about earth’s geologic

history?• 2. What are the steps to an unconformity?

• HW- R&H pp.284-294, A&E #21-52.

Aim: How do we give rocks Absolute Ages?

Do Now:1. What is the geologic

history of NYS chart based on?

2. If I find a coelophysis fossil in a NYS rock. How old is it in years, what time period is it from and where in NYS did I find it?

HW: Complete all questions in Topic 13.

4/7/11

Radioactive Decay-allows us to give rocks absolute age. An atom is made of a

nucleus with protons(+) and neutrons. It is surrounded by electron shells(-).

Elements can have heavier versions of atoms called isotopes where there are extra neutrons in the nucleus.

Isotopes are unstable and decay into different elements overtime in order to become stable. This is called radioactive decay or disintegration.

Half Life A Half Life is the time it

takes for half the atoms in an unstable isotope to turn into a stable element. The length of a half life never changes and is therefore useful in predicting the absolute age of rocks.

Different isotopes have different length 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 once living remains 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