ES-237TEST IS TOMORROW!!

Review on geologic time

• List the 4 eras in order (start with the youngest on top)

• Place the events in each era.• Birds• Plants• Oxygen• Dinosaurs• Horses/elephants• Cambrian Explosion

Try these conversions- You must show your work!

1. 345 mm =_____ m

2. 7,500 cm = ____ m

3. 76 km = ____ m

Percents…1. Sponges first appeared 600,000 years ago. What

percent of the Earth’s history have they been around?

2. 33 out of 50 students are wearing jeans. What percent is this?

3. You get 23 points out of 27 points on a test. What is your percent correct?

4. Write 1/16 as a decimal and a percent.

½ life

1. If you start with 300 g of a radioactive element, how many grams will be left after 3 half-lives? 2. What percent of the original element is left after 3 half-lives? 3. If you have 1000 grams of a radioactive atom that has a half-life of 4 minutes how much of the original element will remain after16 minutes?

1. Which rock is the oldest?2. Youngest? 3. Is the basalt dike older or younger than the

sandstone layer? 4. Conglomerate layer?

• A scientist who studies fossils is a ___.• PALEONTOLOGIST• Nests, tracks, droppings and bite marks are examples

of ____.• TRACE FOSSILS• All fossils form in ____ rock• SEDIMENTARY• What type of dating is used to date fairly young

fossils of once living things?• CARBON-14• Atoms are radioactive because their nuclei are ____.• UNSTABLE

When is the test????

Tomorrow, Thursday, January 24!