| A | B |
|---|
| What does Earth's magnetic field protect earth from? | harmful effects of the solar wind |
| What percent of the atmosphere lies below 50 km | 90 percent |
| less dense air | particles are spread out; denser air has the particles closer together and it is near the bottom; less dense rises to top |
| What is the composition of our atmosphere? | 78 percent Nitrogen, 20.9 percent Oxygen and then other gases make up the rest |
| Equator | Equator in middle; above it is Tropic of Cancer and below it is Tropic of Capricorn |
| When you go into the earth past the surface, what do you find? | Iron 34.6%, Oxygen 29.5%; Silicon 15.2%, 12.7% Magnesium and 8% is the other |
| Earth's interior average density is..... | ~545 g/cm3 |
| What are the Three layers of earth? | inner core, outer core, lower mantle and upper mantle divided by transition zone |
| As you go deeper into the earth | temperature increases |
| What is the core composed of? | iron alloy |
| Composition of Earth's CRUST | Oxygen the most and silicon is second |
| Lithosphere | rock is rigid and cannot flow easily |
| Asthenosphere | rock is still a solid, but can flow |
| Alfred Wegner | he is the German that proiposed that continents can move/are mobile |
| Wegner's hypothesis came from.... | "FIT" of the continents (puzzle like); lcation of glaciations; fossil evidence, rock types and similarities and paleoclimatic evidence |
| What happened to Wegner's theory? | Well, he died in 1930 and since most scientists didn't believe him it died with him until 1950's and then it was revisited again |
| WEGNER WAS RIGHT! | we can measure drift of continents |
| How doe we measure this drifting? | sea floor spreading; subduction and plate tectonics |
| Why did scientists not believe him? | scientists believed the oceans and continents were fiexed and they did not have evidence that they were changes at that time |
| Evidence of drastic changes interpreted as... | shrinkage effects, rebound from thick sediment loaidng, resulting in "upheavel" |
| Wegner's FIT | the continents do fit togehter and it is not a coincidence; and the present shorelines fit roughly and the continental shelf edges make a better fit |
| Glacial Evidence of Wegner's theory: glacial evidence | permian glacial till is found on 4 continents; tills in Africa and India are now near equator |
| Evidence of Wegner's theory: paleoclimatic evidence | tropical coals, tropical reefs, subtropical deserts; subtropical evaporites |
| Wegner's Theory: Fossil Evidence | identical fossils found on widely separated land |
| Mesosaurus fossil | a freshwater reptile |
| glossopteris fossil | subpolar plant with heavy seeds |
| lystrosaurus fossil | non swimming land dwelling reptile |
| cynognathus | non swimming land dwelling reptile |
| xxxxxxxxxx | land dwelling non swimming reptiles could not have crossed the ocean so his drifiting theory was true |
| Matching Geology also makes theory of drift true | geologic structures, rock types and ages are shared in Africa and South America |
| Proterozoic mounts and archean crust | they fit together perfectly South America and Africa (see diagram) |
| Matching mountain belts | Appalachians and Caledonides |
| More criticism of Wegner | Wegner suggested that continents plow through the ocean crust like ice breakers through ice and people did not believe that and since he did not support rotaional forces he was shot down too |
| Arthur Holmes | after Wegner died, he agreed with Wegner because he was responsible for the hypothesis Earth's mantle moved by convection |
| paleomagnetism | see the diagram in binder |
| ocean floor - what surprised oceangraphers? | deepest parts of the ocean occur near land, mountain range runs through EVERY ocena basin, submarine volcanoes form lines across ocean floors |
| sonar mapping on ocean floor defined..... | trenches, mid ocean ridges;seamounts and guyots |
| What is oceanic crust covered with? | sediment |
| Where is the ocean crust thickest? thinnest? | thickest near continents and thinner at mid ocean ridge |
| What is Oceanic Crust made out of? | It is MAFIC (made of basalt and gabbro) |
| if the crust is mafic, it is not made out of what if mafic? | not made of granite rocks or metamorphic rocks |
| What is a characteristic of a mid-ocean ridge? | high heat flow |
| in the oceanic crust earthquakes are limited to what? | part of oceanic fracture zones, mid ocean ridge axes, deep ocean trenches |
| Who was the author/founder of sea floor spreading? | Harry Hess |
| LOOK AT THE HESS/DIETZ DRAWING | in binder |
| Sea floor spreading...what happens | upwelling mantle erupts at mid ocean ridge, new crust moves away from ridges and gathers sediment, and at trenches sea floor dives back into mantle |
| what are anomalies? | linear belts that parallel MOR |
| There are positive and negavite anomalies | SEE DIAGRAM IN BINDER |
| Which direction does magnetism oscillate to the MOR? | perpendicular |
| magnetic reversals | see picture -- magnetic polarity direction of magnetic north; reverse it and north magnetic pole is near south geographic pole |
| How often do magnetic reversals occur? | every 500-700 ka |
| How many have happened since the end of the Cretaceous period? | 171 |
| Proof of sea floor spreading | 1. polarity reversals explain magnetic anomalies 2. positive anomalies- crust with normal polarity 3. negative anomalie -crust with reversed polarity and magnetic anomalies are symmetric across the MOR |
| How do magnetic stripes occur? | as lava cools at MOR |
| Ocean crust spreads away or towards MOR | away |
| SEA FLOOR SPREADING IS THE MECHANISM OF CONTINENTAL DRIFT | KNOW THIS CONCEPT |
| geology | scientific study of Earth |
| physical geology | understanding the processes active at or below the Earth's surface and the materials on which these processes act |
| historical geology | the study of geologic events that have occurred in the past |
| earth sciences | much broader than geology, includes climate, water, carbon resources and so on |
| When was it that we could start to understand Earth in its entirety? | 1960's because of remote sensing like satellites |
| What are the four spheres responsible for maintaing conditions on Earth? | lithosphere, atmosphere, biosphere, hydrosphere |
| lithosphere | rocky surface of Earth |
| atmosphere | the gaseous envelope |
| biosphere | earth's living matter |
| hydrosphere | water, liquid and frozen |
| The Earth System | closed system - balanced no gain or loss of mass or energy; constant exchange between the four spheres; in one sphere is disturbed they all are affected |
| Why is Earth unique? | presence of water in liquid, solid and vapor AND very narro range of surface temperatures |
| Gilbert | scientific method |
| Chamberlin | importance of multiple hypotheses |
| 4 steps of scientific method | observation, classify and group facts, develop 1 or more hypotheses to explain observations, test the validity of hypotheses |
| testing a hypothesis | make predictions; collect new data for these predictions; data confirnms predictions it is looking good; the more predictions confirmed, the greater the hypothesis is in being proven |
| Problems for an earth scientist | only some info is available, process only observed as they are acting now, time scale maky take too long to observe |
| How do we know Earth is round? | xxxx |
| How do we know Earth rotates? | Foucalt |
| What is the radius of Earth? | Erasthenese / 3,900 miles or 6356 km (driving Columbus to Anchorage, Alaska) |
