How long is it estimated to take the ocean's volume of water to ...

[kwoodring]

How long is it estimated to take the ocean's volume of water to circulate through the oceanic crust at
  spreading centers?
  a. 1 million years
  b. 10 million years
  c. 100 million years
  d. 1 billion years

Question 2

If oceanic ridges in the Pacific are more active, then it is expected that the ridges are:a.
   steeper in profile.
  b. narrow.
  c. wide.
  d. the only areas to find transform faults.

[jgranad15]

Answer to Question 1

ANS: B
It is estimated that a volume of water equal to the volume of the world's ocean is thought to circulate
through the hot oceanic crust at spreading centers about every 10 million years. The heat and
chemicals released through this circulation process is thought to play an important role in the chemical
composition of the seafloor and even the atmosphere. Information can be found in the section The
Topography of Deep-Ocean Basins Differs from That of the Continental Margins.

Answer to Question 2

ANS: C
The widest oceanic ridges tend to be in areas that are most active. Fast spreading centers do not build
up in profile because the time it takes for the diverging seafloor to create new crust. The Pacific ocean
has more active spreading centers than the Atlantic. Information can be found in the section The
Topography of Deep-Ocean Basins Differs from That of the Continental Margins.

[kwoodring]

Thanks for the timely response, appreciate it

[xthemafja]

Wow, this really help