Mid ocean ride questions?

Question

What is sea floor spreading?

Where is the oceanic crust densest?

Which denser? Continental or Oceanic crust?

Why is the pacific ocean shrinking?

What effect does the atlantic ocean have on the continents that surround it?

Answer 1

Sea floor spreading is the separation of two divergent plates.  A rift in the crust allows magma to well up and push the seafloor to the side.  This occurs on both sides of the rift.  Eventually the "spreading" sea floor is subducted under a continental crust and occasionally an oceanic plate.  This means that the sea floor is constantly renewing itself.  It also explains why the sea floor rocks are younger than those on continents.

Ocean crust is most dense where it is the coolest.  That would be the crust that is the oldest which is also the crust that is the greatest distance from the min-ocean ridge.

Oceanic crust is denser than continental crust.

The Pacific Ocean is shrinking due to plate movements.  Plate movement is changing the sizes of our oceans and the shapes of our continents. The Pacific plate moves at an absolute motion rate of 4 in per year away from the East Pacific Rise spreading center, the undersea volcanic region in the eastern Pacific Ocean that runs parallel to the western coast of South America. On the other side of the Pacific Ocean, near Japan, the Pacific plate is being subducted, or consumed under, the oceanic arc systems found there. The Pacific Ocean is getting smaller as the North and South American plates move west.

The Atlantic Ocean has a mediating effect on the continents that surround it.  The Atlantic Ocean conatins the Gulf Stream current this is a strong, warm current. The Gulf Stream is influential on the climate of the east coast of Florida, especially southeast Florida helping to keep temperatures warmer than in the rest of the southeastern United States during the winter.  During the summer, the effect is opposite but smaller. The Gulf Stream makes the climate of offshore islands of Massachusetts, Martha's Vineyard, and Nantucket milder than that of Massachusetts Bay, which is isolated from Gulf Stream effects by Cape Cod.

The North Atlantic Current of the Gulf Stream, along with similar warm air currents, helps keep Ireland and the western coast of Great Britain a couple of degrees warmer than the east. However the difference is most dramatic in the western coastal islands of Scotland.

Northern parts of Norway lie close to the Arctic zone, most of which is covered with ice and snow in winter. But almost all of Norway's coast--even that part in the Arctic--remains free of ice and snow throughout the winter due the to warm Gulf Stream.