Is A South Carolina Marriage Recognized In Georgia,Or Is It Legal There?

yes. a marriage that is legal in any state is legal in all others.
a little vaque:

a marriage is recognized in any state: to my knowlege.


Answer:
Yes - any marriage in any state is recognized in all 50 states. This is provided for in the US Constitution.

Most states do not recognize common law marriages, with one exception. Common law marriages which were established in states which *do* recognize them are recognized as fully legal in all 50 states. Example: if a couple in Alabama (where common law marriage is legal) decides to live together as husband and wife and presents themselves to the public as married - they are legally married by the laws of that state. The requirements to establish the common law marriage are cohabitation, intent, and presenting themselves to the public as married. If that couple moves to Florida, which does NOT recognize common law marriage, they are still married.

IF any one state were to legalize gay marriage, then any gay couple who was married in that state could then move to another state which does not recognize gay marriage - and they would still be legally married.
That is not clear cut,

If Massachusetts (or any other state) passes a law saying that same-sex couples can marry, do all other 49 states have to give full faith and credit to that law?

The full faith and credit clause of the Constitution states: 'Full faith and credit shall be given in each state to the public acts, records, and judicial proceedings of every other state.' This seemingly broad rule, however, is not without its exceptions. Importantly, a state may not have to give full faith and credit to a law that violates its 'public policy.' That, of course, raises the question of what a particular state's public policy is. 'States'have been permitted to refuse to recognize marriages from states with different policies toward polygamy, miscegenation, or consanguinity for decades.'

So, in your case unless it is a particulary unusual or controversial marriage, probably yes. If it unusual, 16 year old marries 20 year old cousing, happens in Georgia and South carolina, but against public policy.....maybe no.

Sorry wibelle3 - but your understanding of The full faith and credit clause of the Constitution is incomplete and your answer is somewhat incorrect.