Geology!

1. Geology! Like Rocks and Stuff…

2. What is Geology? • The study of the “Physical” World and it’s natural processes. • Earth’s History! Why Do we care?

3. What do Geologists study? Earthquakes Rocks and Minerals Fossils/Earth History Volcanoes Erosion

4. So let’s look at an Earth History problem: Alfred Wagener noticed that several continents seem to fit together really well (like pieces of a puzzle) For example: Africa and South American’s coastlines almost Look made for each other… In fact, lots of the continents seem to fit together like a HUGE puzzle! Is it just a coincidence?

5. Fig. 2.05 W. W. Norton. Modified from Motz. None of these organisms are ocean living organisms capable of swimming for Thousands of mile. So how did their fossils get so wide spread? • Also the fossils of the exact same critters were found on two different continents. THAT WERE SEPARATED BY AN OCEAN!!!yeah…that shouldn’t happen…

6. So… • We have two big phenomenon that are difficult to explain: • That the continents look like giant pieces of a puzzle. • Fossils of the same non-swimming organisms found on land separated by an ocean Main Concept One: All the continents used to be joined together in one large piece called “Pangea”. Wagener reasoned that all of the continents must have been joined together at some past time!!!

7. So…think: What force is strong enough to move entire continents? No really! THINK for a minute…. Don’t just give up and click through! THINK!!! What force could be strong enough to move an entire continent? Wagener's Problem: How do you get an entire continent to move? In fact, Wagener’s ideas were rejected at first because nobody could believe there was a force strong enough to move an entire continent…but then the answer was discovered!

8. So which form of energy makes the Earth’s continents move about? Heat Energy! Main Concept Two: Heat deep in the center of the earth (the Core) creates enough force to drive the process of change on the surface.

9. Remember your layers of the Earth (from 7th grade): • Inner Core • Solid • Outer Core • Liquid • Mantle • Soft Solid • Crust • Continental (land) • Ocean

10. Heat energy is what makes motion and change on the Earth’s surface! We already know that when fluid is heated, it moves in a circular motion: “CONVECTION”

11. What is Happening below the earth’s surface?Convection within the Mantle! Notice that the rock in the Mantle begins to move in A circular motion = Convection! VERY SOFT ROCK VERY SOFT ROCK Primary Source of Heat Energy

12. As the mantle moves around, the crust “floating” on top of it is “deformed” into different shapes and features! These features include: Mountains, valleys, canyons, volcanoes, oceans, deep sea trenches, etc… Fig. 2.06b W. W. Norton

13. So how do we get these different features from mantle movement? • http://education.sdsc.edu/optiputer/flash/convection.htm • Watch what happens as: • Continents collide. (What is formed?) • Continents “drift” apart. (What is formed?) Since Wagener’s day we have observed new evidence/phenomena that helps to support his idea that the continents are indeed moving: Some are found on the next few slides…

14. Evidence #1: We have discovered that the age of rocks on the sea floor change as you move away from the middle of the oceans. The youngest rocks are in the middle; the oldest are at the edges. This is an image of the Atlantic Ocean bottom. The ages of rocks are shown by colors. Blues and greens are the oldest Reds and oranges are the youngest

15. Evidence #2: Locations of Earthquakes and Volcanoes infer big cracks in the crust! We call the pieces of crust : “Plates” These “plates” act like floating rafts on the mantle

16. Evidence #3: We have used GPS technology to actually track the movement of land. The arrows show where the areas are currently moving. There is more evidence, but these three are very convincing! Motion of Plates

17. Where the “plates” touch each other, they form three types of cracks/edges that we call: “boundaries”: *Divergent: Where two plates move apart *Convergent: Where two plates collide into each other *Transform: Where two plates slide past each other.

18. Divergent Plate Boundary -Most common in the middle of oceans (mid-ocean ridges) In fact, scientists think this is how new oceans are formed! -Two plate moving apart from each other -Many small Volcanoes -Many small earthquakes

19. A? B? C? Two plates diverging! Which group of volcanoes is probably older? A: C is the oldest! And the old rock is on the outer edge Notice that the young rock is right down the middle This group of volcanoes used to be closer to the Mid-Ocean Ridge! The red colors shows the youngest rock and the blue colors show the oldest rock!

20. Convergent Plate Boundary -Where two plates collide with one another -Most common at the edge of oceans -Few, very large earthquakes -Large volcanoes/ mountains form nearby (tallest places on earth) -Deep sea trench (deepest places on earth)

21. What is all this white stuff on top of? A: Snow on Mountains What are all these little islands? A: Volcanoes! What is this dark long feature? A: A deep trench! Ocean Plate colliding with Continental Plate

22. Continental Plate colliding with Continental Plate Why is there no trench? What has formed here? A: Neither plate is going down! A: Very tall mountains! Will you find volcanoes here? A: Probably not. There is no crust being melted

23. Transform Plate Boundary Transform Plate Boundary -Most common between the other plate boundaries. -Two plates moving side by side -“Offset” features help identify movement -Common medium sized earthquakes “Offset” river