posted by kathy on .
Explain why condensation forms on a glass containing a cold drink?
Warm atmosphere around the glass causes the vapors in the air to turn to liquid.
First, plot some of the data to get an idea of distances and scales, etc. Let's make a cross-section of the data as best we can.
Calculate the depth to the ocean crust (water depth plus sediment thickness). Now plot this depth versus longitude. The transect line was designed to cross over the mid-ocean ridge. [Hint: If you make the depths negative numbers, the graphs will look more like a physical cross section, i.e., depth will increase downward. The Excel spreadsheet already has this sign change included.]
None of the holes was drilled directly on the crest of the mid-ocean ridge, probably because it would be a difficult drilling environment. At what degree longitude is the mid-ocean ridge along this east-west transect? Locate the position of the mid-ocean ridge on this graph. (On your graph of depth versus longitude, show the technique you used to locate the location of the ridge.) [It is a good idea to email the ridge longitude and a brief description of how you determined it to the instructor to have it checked before you go too far. It can save you a lot of wasted time.] Now calculate the distance from the mid-ocean ridge to each of the sites. Give your answers in kilometers. Use the following information to convert degrees longitude to km.
Because the earth is 'round', at the equator 1o of longitude = 1o of latitude; the distance from the north pole to the equator is about 10,000 km and corresponds to 90o. How many kilometers correspond to 1o?
Use the conversion factor to complete the table above. Be aware of which sites are east or west of the ridge but treat all of the distances as positive.
For each of the 3 following relationships, plot a graph and interpret the results
age of the "first" sediment (age at base of sediment) versus distance from the mid-ocean ridge (i.e. time versus distance).
What is the relation of age versus distance?
Why does this relation occur?
Can this relation be used to estimate how fast (speed = distance/time) the mid-ocean floor is spreading?
If so, how fast is the sea floor spreading (in cm/year)?
sediment thickness versus age of the first sediment (i.e. meters versus time).
Where is the oldest sediment located? Why? (See page 61; figure3.25)
What is the rate of sediment accumulation (meters/million years)?
Recalculate the rate in terms of cm/1000 years. Check your answer.
Is this rate reasonable?
age of the first sediment versus depth of the ocean crust (i.e. time versus depth).
What is the relation? Why?
What does this tell us about the ocean crust?