Homeroom

Do Not Walk Around!

Warm-up-pg. 22-Dinosaur Extinction Theories

• Draw a cartoon geologic time scale that includes the following:

Precambrian timePaleozoic eraMesozoic eraCenozoic era and one geological event for each

This will receive a grade. I will be coming around to check.

Warm up-pg. 19-Geologic Time Scale1. What is radioactive decay?2. What is a half life?3. Where is the oldest

rock?4. Where is the youngest? 5. The chart shows which

scientific concept?6. List an example of absolute dating and relative

dating.

Warm-up-pg.21-Geo. Time Scale Day 2

Relative Dating Absolute DatingBoth

Complete the chart!

Index Fossils • Organisms that lived during a specific time

• IDENTIFY THE AGE OF ROCK THEY ARE FOUND IN

• INDEX FOSSILS MUST BE WIDE SPREAD

Ice Cores

• Long column of ice drilled out

• Contains bubbles with air from thousands of years ago.

• Only type of fossil dating that gives us glues about the past atmospheric conditions.

• Trilobites - small, hard-shelled organisms that lived in ocean.

• Considered to be index fossils.

Geologic Time

Eon Largest group of the history of the Earth

First 3 eons = Precambrian time/Era

4th eon is the Phanerozoic eon

Precambrian• Longest time in Earth’s History.• Very few life forms existed.• Bacteria first form of life; created oxygen which

changed Earth’s atmosphere.

ERAS Eons divided into eras. Most recent eon is

divided into three eras.

-Paleozoic-Mesozoic-Cenozoic

**End of eras are marked by mass extinctions**Period: Each era divided into even smaller periods.

Paleozoic Era • Beginning-ocean life

• End of era-reptiles, amphibians, ferns

• Greatest extinction of all time

Mesozoic Era • Dinosaurs

• Some mammals, birds, and flowering plants evolved

• Pangaea

• Scientist think era ended with mass extinction caused by an asteroid hitting the Earth.

Cenozoic Era Current era-began 65 million years ago

• Age of the Mammals!!!

• The era we live in

Oldest rock layers

First Bacteria

Precambrian

Pale

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cM

esoz

oic

Geologic Time Scale Questions-answer on pg. 21

1. What is the longest time period in earth’s history?

2. When did the first single celled organisms show up? How long after earth formed did this happen?

3. When did Pangaea begin to split up?4. When did the earliest humans appear and in

which era?

Geologic Time Scale Music Video

Asteroid Impact

• 10k wide asteroid struck Earth• Dust thrown into the air• No light and plants died

• Huge grater near Mexico

• Fossils show that dinosaurs died before 65 million years ago.

Excessive Volcanoes

• Series of volcanic eruptions wiped them out• Let out huge amounts of sulfur dioxide• Made Earth cold

• Ancient lava flow the size of France in India

• A layer of soot is found in rocks all over the world that are 65 million years old. (supports asteroid impact)

Radiation

• A star exploded as a supernova and produced a wave of cosmic radiation.

• Everything was fried.

• Fossils from 65 million years ago show radiation.

• No evidence that this radiation came from space.

Ice Age

• Earth was plunged into a winder by an unknown event that blocked out the sun.

• Plants could not grow.

• Researchers have found cold water plankton fossils in a warm sea off of Africa.

• The fossils are 65 million years old and show a sudden drop in temp.

• Scientists cannot explain what caused the sudden drop.