1. 1Daily Warm-Up Exercises Day 28 What are destructive Earth processes? Destructive processes break down old landforms. examples: weathering; erosion; tectonic plates sinking and melting Constructive processes build new land forms. examples: mountain building; deposition; new crust formation What are constructive Earth processes?

2. 2 Mini Geologic Time Lines (Part 3) Investigation 6 It's About Time

3. 33 Mini Time Lines Each pair will make a time line on adding- machine tape. Your time line should be 4.5 meters long to show all of Earth history. We will only use 70 cm. What scale will we need to use to represent 4.5 billion years? 1 mm = 1 million years

4. 44 Geological Eras Geologists have divided Earth's history into four eras based on the kinds of organisms that existed at the time. Cenozoic Mesozoic Paleozoic Precambrian

5. 55 Geological Periods Geologists further divided the eras into periods based on major events that took place in Earth's crust. For example, the Mesozoic Era is divided into three periods. Mesozoic Era Cretaceous period Jurassic period Triassic period

6. 66 Now  Turn to the Earth History Time Line on page 51. Your task is to divide your 4.5- meter adding-machine tape into eras and periods. Our time line will be 70 cm.  Draw a line at one end of your tape and label it "Now."

7. 77 Quaternary Period  The Quaternary period started 1.6 mya. How many millimeters is that? 1 million years = 1 millimeter, so 1.6 million years = 1.6 millimeters  Draw a line 1.6 mm from the Now line and label that tiny section the "Quaternary Period."

8. 88 Tertiary Period  The Tertiary period started 66 mya. How many millimeters is that?  Draw a line 6.6 cm from the Now line and label that section the Tertiary Period." 1 million years = 1 millimeter, so 66 million years = 6.6 centimeters

9. 99 VERY IMPORTANT!!!  All measurements must be made from the Now line.  The zero end of the ruler must always stay on the Now line.

10. 10 Mark Eras  When you finish all the periods, go back and draw a heavy line to mark the beginning of each era.  Label the era by writing its name across the periods.