| 1.) Typical continental crust
over magma. |
| 2.) Hot magma pushes up under
the crust. Cracks allow magma to reach the surface. |
| 3.) Release of magma and
slight separation causes the crust to crack more. |
| 4.) More separation allows the
middle to collapse. This sunken area allows water to
collect. Hot springs and volcano activity occur because
magma is very close to the surface. |
| 5.) Magma comes close to the
surface and cools. New ocean crust begins to form as major
separation begins. Middle areas are not below sea level
but the seas are shallow. |
| 6.) Separation continues but
oceans are still shallow. Ocean floor buildup continues. |
| 7.) Separation continues with
a lot of sediment on the ocean edges. These sediments have
been washed out to sea by rivers. The new ocean crust
carries the magnetic patterns of changes in the earth's magnetic
field. |
| 8.) Separation continues but
the oceans are deeper. |
| 9.) Zones of weakness occur
where the continent and crust meet. These zones form the
place for downward convection currents. Ocean trenches
occur here. New mountain ranges occur because ocean crust
pushes on the continental crust causing its sedimentary rock to
fold into tall mountains. |
