Oceanography Name(s)­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ Paul Peritz Discussion #1 (15 points) Directions: Answer the following questions as thoroughly as possible using your class notes and the lecture textbook.

1. Briefly describe the 4 major disciplines of Oceanography? What does each entail?
1.) Geological Oceanography – shape of the sea floor, how it changed through time, arrangements of continents, sediments.
2.) Chemical Oceanography – chemistry of seawater. Study of the chemical composition & properties of seawater; how to extract certain chemicals from seawater, & effects of pollutants.
3.) Physical Oceanography – waves, tides, currents, and weather, & the transmission of light & sounds in the oceans.
4.) Biological Oceanography – life of the oceans.

2. Why do we describe the Earth as being a “system”? What are the 4 sub-systems/spheres of the Earth? Briefly describe each of these.

The Earth is a system which is a group of interacting parts directed by the flow of energy.
1.) Hydrosphere – all water on earth, covers 71% of earth’s surface.
2.) Atmosphere – gaseous “blanket” controls weather/climate, gives possibility of life
3.) Geosphere – solid earth, the rock, arranged in “layers”
4.) Biosphere – all life on earth (past & present) would not exist without right combination of hydro, atmo & geosphere.

3. Explain how the earth achieved its layered nature as it cooled after forming.
Density Stratification: densest “stuff” sinks, lightest “stuff” floats. This results in a layered Earth with densest “stuff” in the interior.

4. What is the difference between the lithosphere and the asthenosphere?
Lithosphere – cool, rigid outer shell, brittle behavior (rock) 100 km thick
Asthenosphere – below lithosphere, hot, weak, and plastic behavior

5. Name and briefly describe each of the 5 oceans.
1.) Pacific – largest in area & volume also deepest, circular shaped, very geologically active (“The Ring of Fire”) shrinking
2.) Atlantic – 2nd largest, s shaped, geologically inactive, growing (spreading)
3.) Indian – mostly in the southern hemisphere, triangular shaped
4.) Artic – small, shallow. Mostly covered by ice
5.) Southern – southern hemisphere, boundaries defined by meeting of ocean currents

6. What is Echo Sounding? How does it work? (Give an equation with your explanation.)
Echo Sounding is using sound waves to measure bathymetry. Ships send a sound signal down to ocean floor, measures time until return

7. Define Evolution and Natural Selection.
Evolution – groups of organisms (slowly, stepwise) adapt & change through time because of naturally occurring variations in populations. In a big place (Earth) with lots of time (4 Ba) living things change & spread out.
Natural Selection – only best adapted organisms survive in certain environments long enough to reproduce & (pass along genetic material)

8. What evidence did Alfred Wegener use in order to support his theory of Continental Drift? Where did he go wrong?
1.) fitting of continents
2.) fossil evidence
3.) structural evidence
4.) Paleo-(ancient) climates
Problems with Wegener’s theory: he matched the shore lines, which constantly change daily. Continents “plow through” stationary oceans – physically impossible

9. What are magnetic anomaly stripes? How did they help support the idea that the continents were moving around?
Magnetic anomaly stripes – a distortion of the regular pattern of Earth’s magnetic field resulting from the various magnetic properties of local concentrations of ferromagnetic minerals in Earth’s crust.
Palaemagnetic evidence – magnetic north moves sometimes flips, signature is recorded by rocks with Fe, magnetic anomaly stripes at spreading centers: results in symmetrical stripes indicating polarity reversals.

10. What are mid-ocean ridges? How do they form? What are the names of 2 mid-ocean ridges?
Mid-ocean ridges – composed of shallower areas near the middle of an