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CM Earth Science 3-2
Unit 3 Mr. Wilbur/Barbis: Chapter 10
| Question | Answer |
|---|---|
| What are 4 evidences that supported Wegener’s continental drift hypothesis? | Alfred Wegener (1912) produced theory since the coastlines seem to fit like a puzzle, there must have been a “supercontinent” Pangaea that broke apart and drifted. EVIDENCE: puzzle fit, fossils, rock formations, climate |
| Why was Wegener’s hypothesis rejected by most geologists of his time? | he thought continents “plowed” through the ocean basin, but was no evidence to support this |
| What 2 discoveries about the seafloor were made regarding the Mid-Atlantic Ridge? | The sediment that covers the sea floor is thinner closer to a ridge than it is farther from the ridge;The ocean floor is very young |
| Continental drift | The hypothesis that states that the continents formed a single landmass, broke up, and drifted to their present locations |
| Mid-ocean ridge | Long, undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the asthenosphere and creates new ocean lithosphere as tectonic plates move apart |
| What process did Hess hypothesize as the cause of the observations of the sea floor? (sea-floor spreading) | Process by which new oceanic lithosphere (sea floor) forms as magma rises to Earth’s surface and solidifies at mid-ocean ridge |
| Paleomagnetism | Study of the alignment of magnetic minerals in rock specifically relating to reversal of Earth’s magnetic poles, also magnetic properties that rock acquires during formation |
| How did the study of magnetic reversals lend support to sea floor spreading? | pattern on one side of ridge is mirrored on the other side |
| Plate tectonics | Lithosphere made of plates “riding” on asthenosphere |
| Continental plate | Plate with a continent on it; made of both continental and oceanic plate |
| Oceanic plate | Plate without continent on it; only oceanic crust |
| Evidence for plate tectonics | Mid-oceans ridges: world’s largest mountain range, very active volcanoes;Earthquake & volcanic patterns;Shapes of the continents along the Atlantic coast |
| Age of sea floor | Youngest rocks at ridges; age increases with increased distance from ridge;Same pattern mirrored on either side of ridge;Oldest rocks are Jurassic Period (190 million years old); older rocks on continents dating back 3.5 billion years old |
| Patterns of magnetic reversals | Pattern on one side of ridge mirrored on other side |
| Heat flow from interior | Greatest along ridge, decreases with distance from ridge |
| Fossil evidence | Similar fossils found on widely separated landmasses |
| Similar rock and mountain formations | Similar rock and mountain formations |
| Processes affecting Earth’s surface | Volcanism;Crustal movement (plate tectonics) Attempt to make surface uneven & rugged, energy comes from inside the Earth |
| Lithosphere | The solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle |
| Asthenosphere | The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it |
| What 2 major Earth events occur along plate boundaries? | earthquakes; volcanoes |
| Three types of plate boundaries | divergent; transform; convergent |
| Divergent boundary | plates moving apart, mid ocean ridge forms on sea floor; rift valleys form continents, active volcanoes; shallow earthquakes |
| Transform boundary | plates slide past each other; shallow earthquakes are common |
| Convergent boundary | plates come together |
| Destructive processes | Weathering; Erosion |
| Energy from Sun | Processes working to level Earth’s surface |
| Characteristics of an area depend on | Balance between construction and destruction |
| Dynamic equilibrium | Exists if the opposing processes are balanced |
| Two features found where plates are moving apart | Rifts and mid-ocean ridges |
| Type of boundary where magma not produced | Transform |
| Ridge push | Cooling rocks sink, asthenosphere below it exerts force on the rest of the plate |
| Slab pull | Leading edge of plate sinks, pulls rest of the plate along behind it |
| Rifting | Process by which Earth’s crust breaks apart; can occur within continental or oceanic crust |
| Terrain | Piece of lithosphere that has a unique geologic history and that may be part of a larger piece of lithosphere such as a continent |
| Shields vs. cratons | All continents contain large areas of stable rocks called cratons and within cratons that have been exposed at Earth’s surface |
| 2 major impacts that moving continents have on Earth | Changes in climate: ice covered Earth; temperature changes;Changes in life: new populations and others go extinct |
| Supercontinent | Continents arranged in large land masses |
| Last supercontinent | Pangaea formed 300 million years ago |
| When did Pangaea start to break apart? | 250 million years ago |
| What ocean formed as the American continents separated from Europe and Africa | Atlantic Ocean |
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vbarbis
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