Seafloor and Plate Tectonics
What ocean-floor feature is the deepest, steepest depression in the ocean?
Trench
What type of molecule has a slightly positive end and a slightly negative end?
Polar molecule
What is the measure of dissolved salts in water called?
Salinity
As ocean depth increases, what happens to pressure?
Increases
Sound travels faster in water or air?
Water
What type of boundary occurs when two plates move apart?
Divergent boundary
Which end of a water molecule is slightly negative: oxygen or hydrogen?
Oxygen
What is the average salinity of the ocean?
35 ppt
What is the layer where temperature drops rapidly with depth?
Thermocline
What is the term for how often a sound wave repeats itself?
Frequency
What process occurs when one plate sinks underneath another?
Subduction
Water dissolves salt, but did not dissolve oil well in your lab. What property of water were you investigating?
Universal solvent
Heavy rainfall and river runoff cause salinity to increase or decrease?
Decrease
Which color of visible light penetrates deepest into the ocean?
Blue
Which travels farther: high-frequency or low-frequency sound?
Low-frequency
Which type of plate boundary can form trenches, volcanoes, and mountains?
Convergent boundary
Why is water called a universal solvent?
It can dissolve many substances
Which would most likely have higher salinity: a hot, dry ocean region with high evaporation OR an area receiving lots of rainfall?
Hot, dry region with high evaporation
What is the area with lower-than-normal dissolved oxygen called?
Oxygen minimum layer
About how deep is the Deep Sound Channel?
1,000m
Rocks are youngest near a mid-ocean ridge and older farther away. What does this provide evidence for?
Seafloor spreading
Water is a polar molecule. How does this help explain why the ocean contains dissolved salts?
Water's positive and negative charges pull salt ions apart, allowing them to dissolve.
A 1-liter (1,000 g) sample of seawater has a salinity of 40 ppt.
A. How many grams are salt?
B. How many grams are pure water?
A. 40 g salt
B. 960 g pure water
A fish lives in the Twilight Zone. Which conditions would you expect for temperature, light,, oxygen and pressure?
Cooler, limited light, low oxygen, high pressure
A whale needs its sound to travel thousands of kilometers. What type of sound AND ocean feature would help?
Low frequency
Deep Sound Channel