Continental Margins

A continental margin, the edge of the continent, is defined by the presence or absence of a nearby plate boundary, and a change in the type of crust: continental on one side of the boundary, oceanic on the other.  There are two types of margin, but three types of  plate boundary because a boundary can occur within a continent, or which solely oceanic crust.

Continental margin Plate Boundary Nearby Continental shelf width Associated Geologic Hazards Resources
Active/Pacific type Conservative or destructive near margin Generally narrow Volcanoes, earthquakes, tsunamis Oil/gas, minerals
Passive/Atlantic type None  (constructive has rifted away, and over time will be far away ("mid-ocean") Generally wide None Oil/gas

 

Passive margin.

Joshua Doubek, Wikipedia.

We will discuss Isostasy and rock density later, which will help explain why the layers have the thicknesses and depths they do.


Last revision 8/24/2016