Do First Questions On Moday write Labor Day

Do First Questions: On Moday write Labor Day for both sides On Tuesday write SLO Testing for both sides On Wednesday write Test for both sides Today: • Draw and label the diagram of the mechanical layers of the earth

Agenda • Retake Policy • Plate Tectonic Guided Notes • Self-Directed Plate Practice

Test Corrections • If your overall grade is a 75 or less then you can complete a test corrections afterschool or in the morning • If you scored a 55 or higher, the test corrections will get you to a 70 • If you scored less than a 55, you must do an hour of remediation with me before you can do test corrections

What are Tectonic Plates? • Tectonic plates are pieces of Earth's crust and uppermost mantle, together called the lithosphere.

Evidence of Tectonic Plates Continental Drift Theory 1. Coastline Matching 2. Fossil Evidence 3. Rock types and structures Theory of Plate Tectonics 4. Mid Atlantic Ridge 5. Age of Sea floor 6. Paleomagnetism

Alfred Wegner • He was a German researcher who proposed the continental drift theory • The continental drift theory states that the continents had once been joined to form a single supercontinent named Pangea 200 million years ago • He was the first to propose the continents could move

Wegener • Watch the short clip and answer why Wegner’s idea was not supported • http: //www. pbslearningmedia. org/resource/e ss 05. sci. ess. earthsys. wegener 1/platetectonics-the-scientist-behind-theory/

1. Coastline Matching • Continents fit together like a puzzle

• If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.

2. Fossil Evidence • Same fossils were found on different continents. • The fossils were of organisms that could not cross oceans.

3. Rock Types and Structures • Several mountain belts end at one coastline, reappear on a landmass across the ocean.

3. Rock Types and Structures • Evidence of glaciers has been found in areas with high temperatures

So far Wegener is supported But was he right?

He was only partially correct. Continental drift was replaced with theory of plate tectonics because the lithosphere “plates” were moving not the continents.

4. Mid - Atlantic Ridge • The Mid Atlantic ridge is mostly underwater and spews lava which when hardened produces new rock. • The new rock pushes away old rock • The new rock is new lithosphere.

5. Age of the Sea Floor The age of the crust near ridges is younger than the crust near the continents bordering the ridges

6. Paleomagnetism • Paleomagnetism is the natural magnetism in rock bodies. • This permanent magnetization acquired by rock can be used to determine the location of the magnetic poles at the time the rock became magnetized – Normal polarity—when rocks show the same magnetism as the present magnetism field – Reverse polarity—when rocks show the opposite magnetism as the present magnetism field

• The alternating polarity shows that new lithosphere has been formed over time

Theory of Plate Tectonics • All the evidence shows: 1. The Earth is creating new lithosphere “plates” 2. The lithosphere “plates” have moved over time 3. The lithosphere “plates” are still moving

Self Directed Plate Practice • Answer the questions • Cut and paste the continents together to show Wegner’s theory – Make sure to label the continents

DYL • 1. Why is the term plate tectonics more correct than using continental drift? • 2. How did the age of sea floor support the idea of plate tectonics? • 3. What is paleomagnetism?