1Daily Warm-Up Exercises1 Day 23 What is the main ingredient in limestone? calcium carbonate What was the purpose of the seawater investigation we did on Day 22? The purpose was to try to find out where the calcium carbonate comes from and how it gets into limestone.

2 Testing for Calcium Carbonate (Part 2) Investigation 5 Limestone

3 Review Limewater Investigation Why did we blow into the limewater? The limewater represented ancient seawater. Blowing into it simulated marine organisms exhaling in an ancient sea. What happened? The water got cloudy and a white powder settled to the bottom of the cup.

4 Plan an Investigation We have some materials that might be found in the sea. Plan an investigation to see if any of these materials might cause limestone to fizz. Make a chart on the back of lab sheet 37 to organize your observations.

5 Results Which materials fizzed in acid?  white powder  oyster shells  Other shells How do you think limestone forms? What process might produce a rock that fizzes? Write your thoughts on the back of your lab sheet.

6 Calcite Limestones fizz in acid because they contain calcite (calcium carbonate) When acid reacts with calcite, carbon dioxide gas is produced. The fizzing is the CO 2 being released. Where does the calcite come from?

7 One Way Some marine organisms have shells made of calcite. When the animals die, the shells settle to the bottom. Layers pile up, and the shells get compacted and cemented together to form limestone.

8 Another Way Marine organisms exhale CO 2 into the seawater. The CO 2 reacts with calcium in the water to form calcite powder. The calcite powder settles to the bottom and gets compacted and cemented together to form limestone.

9 Finish Seawater Investigation Answer the questions at the bottom of the Seawater Investigation worksheet. Finish reading Coconino Stories pg. 73 Define in your journals: –Crossbedding –Uniformitarianism

Crossbedding

Uniformitarianism The present is the key to the past Geologists assume that the processes (deposition, erosion, etc) they see happening today work exactly the same way through out geological history. 13