Daily Review #3 8. Tell the rock’s story…

Composition of Earth 3 layers ◦ Based on compounds present ◦ Density differences Crust ◦ Outermost ◦ km ◦ Thinnest layer ◦ Types  Continental  Oceanic

Mantle Middle layer 2900 km thick Never visited Conclusions based on observations on Earth surface  Oceanic volcanoes

Core Center Radius of 3430 km Mostly Fe, some Ni ◦ High density ◦ 1/3 of Earth’s mass

Physical Structure Lithosphere ◦ Solid, outer layer ◦ Crust +upper mantle Asthenosphere ◦ Solid, slow flowing rock ◦ Mantle

Outer core ◦ Liquid layer Inner core ◦ Center ◦ Solid, dense

Mapping Interior No drilling past crust Seismographs ◦ Earthquakes ◦ Wave speed effected by density and thickness ◦ Study times to pick up seismic waves

Remember…. Observation Inference

Continents Let’s identify and label the different continents on our blank map. ◦ North America ◦ South America ◦ Africa ◦ Europe ◦ Asia/India ◦ Australia ◦ Antarctica Also identify the Atlantic and Pacific Oceans

Take 2 minutes to observe the world map. ◦ Make 3 observations about the continents coast lines. ◦ Make 1 inference based on your observation End

Puzzle ◦ Work with your partner to try and fit the continent puzzle pieces together.

Do they fit together perfectly? What may have caused the coastlines to change over time? ◦ Come up with 2 possible reasons (2 minutes) End

Look at the small pictures on your puzzle pieces. Those are fossils found in those areas of each continent. Rearrange your puzzle so that all of the fossil segments line up. (2 minutes) End

Take 3 minutes to observe the fossil placement. ◦ Make 3 observations (the same fossils are on more than one continent) ◦ Make 1 inference End

Take 2 minutes to draw in dots along the plate boundaries to show recent earthquakes. (large dots = more activity, small dots = less activity) End

Take 2 minutes to draw in triangles to show volcanic activity. End

Take 2 minutes to observe the marks you just made on your map. ◦ Make 3 observations (earthquakes and volcanoes occur in the same sorts of locations) ◦ Make 1 inference End

Observations/Inference – compare tectonics map and volcanoes/earthquakes map End

Plate Tectonics Plates ◦ Divisions of lithosphere ◦ Moving on asthenosphere

Wegener – Continental Drift Theory Early 1900s Once single landmass - Pangaea Broke up – Laurasia, Gondwana Drifted to present location

Continental Drift Evidence For Wegener ◦ Fitting together of continents ◦ Similar things on distant continents  Fossils  R ocks

How would you explain this evidence?

Sea-Floor Spreading Evidence for continental drift Mid-ocean ridges ◦ Tectonic plates moving separating ◦ New magma rises ◦ Form new oceanic crust ◦ Older crust pushed away

Magnetic Reversals Evidence for continental drift Molten rock ◦ Magnetic minerals ◦ Align with magnetic field Magnetic field reverses ◦ 177 times in 85 million years ◦ Last 600,000 years ago Recorded in rock ◦ Similar pattern to age of rocks

Causes for Plate Tectonics Convection ◦ Asthenosphere ◦ Heated rock  Expands and rises ◦ Cools  More dense ◦ This movement causes plate movement